Amazfit Stratos (Smartwatch 2 / 2S)
The Amazfit Stratos, sometimes also found under the name Amazfit Sport Smartwatch 2, was officially released in China on December 12, 2017. The smartwatch was released in a standard and a premium version. The smartwatch is produced by the Chinese wearable manufacturer Huami, which among other things also makes wearables for Xiaomi.
An international version of the sports smartwatch was released at the end of February 2018. Apps specifically intended for the Chinese market have been removed and the user interface has been adapted in several languages.
Design, workmanship and delivery
Standard model vs. Premium model
Before we look at all the features of the smartwatch, let's first look at the difference between the two Chinese models and the internationally released Amazfit Stratos. In China, the standard model was published under the name Amazfit Smartwatch 2, the premium model as Amazfit Smartwatch 2S. The only differences between the two versions are the display glass used and the watch strap. The standard model uses a conventional, hardened display glass and a silicone wristband. The premium model, on the other hand, uses sapphire glass and a leather strap. The watch strap is interchangeable on both models.
The smartwatch appeared internationally as the Amazfit Stratos. This is the Chinese standard model with a customized user interface. A premium variant has not been released for the international market!
watch case
The design of the new Amazfit Smartwatch is completely different from the design of the Amazfit Pace . Overall, the watch case of the Amazfit Smartwatch 2 appears much more massive, but is still based on a sporty style. The housing is made of carbon fiber reinforced plastic in the typical carbon look. The diameter is 4.8 cm, the height 1.5 cm and the weight of the smartwatch including the watch strap is exactly 60g.
On the top is the transflective display with a 1.34 inch diagonal. The display is surrounded by an elegant ceramic bezel. The Amazfit Stratos can be actively controlled via three stainless steel buttons (316L) placed on the side. The 4-pin charging connector and the slightly protruding heart rate sensor are located on the underside. The smartwatch cannot be opened, so that no access to the battery or the internal hardware is possible.
A clear advantage over the previous model is the classification (protection class IP68) as waterproof up to 5 bar (5 ATM / 50 meters). Under normal conditions, it is thus possible to shower, swim and also dive with the smartwatch.
Watch strap and build quality
The silicone bracelet is adjustable in size in 15 steps and is closed with a pin buckle. The band length is 20 cm, the band width is 22 mm. A quick release makes it easy to change the bracelet.
The processing quality of the actual smartwatch is nothing to complain about. However, the watch strap, which shows slight signs of wear and tear after just a few weeks, is criticized. In addition to the Amazfit Smartwatch 2, the scope of delivery includes a charging station with USB connection option and a user manual.
Display
"Transflective display"
The color display has a diagonal of 1.34 inches. The resolution is 320 x 300 pixels. Like the display of the Amazfit Pace, the new Amazfit Smartwatch 2 also uses a so-called "transflective display". This type of display does not have a backlight and reflects incident light. The display is always active as "Always-On" so that the display does not have to be switched on to read the time.
Further advantages of a transflective display are above all the particularly good readability in sunshine and the low energy consumption. However, there are also disadvantages, such as a comparatively low viewing angle stability and mostly pale color reproduction. Equipped with a touchscreen, the smartwatch can be operated not only via the control buttons on the side, but also directly via the display.
The transflective display convinces in the test. Especially in sunshine or direct light, the display of the Amazfit Smartwatch 2 is very readable. Smartwatches with conventional LCD or AMOLED display is the Stratos ahead. In low light conditions, however, the readability decreases.
Backlight
In order to be able to use the smartwatch in the dark, the display is also equipped with a background lighting that is activated at the push of a button or by lifting the arm. An ambient light sensor, which is located below the display, regulates the brightness of the background lighting according to the ambient light. What you also have to put up with are the sometimes pale colors that appear more or less strong depending on the incidence of light. The operation via the small touchscreen works well. Inputs and swiping movements are precisely recognized.
screen protector
The display of the Amazfit Smartwatch 2 is protected by a hardened display glass. The premium model (Smartwatch 2S) uses higher quality sapphire crystal. In a test lasting several weeks, the conventional, hardened display glass proved to be extremely scratch-resistant and shock-proof. The smartwatch even survived an unintentional fall from 1.5 meters undamaged.
Hardware
The internal hardware equipment of the Amazfit Stratos does not differ from the previous model. Huami continues to rely on a dual-core processor that clocks at up to 1.2 GHz, 512MB of RAM and 4GB of flash memory. The system already takes up a full 2GB of internal flash memory, which is why the user only has 2GB of remaining storage space. There is no memory expansion option!
Further hardware features are a WiFi module (802.11 b / g), a Bluetooth 4.0 module, a GPS module, a PPG heart rate sensor, an acceleration sensor, a gyroscope, a magnetic sensor, a barometer and an ambient light sensor.
OPERATION
Before you decide on the Amazfit Stratos, you should be aware that the Smartwatch was initially released for the Chinese market. The smartwatch has also been available in an international version since the end of February. Before buying, you should pay attention to which version you choose. The Chinese model is usually cheaper, but also only offers a Chinese user interface. With knowledge, however, a Chinese model can also be converted into an international model with a multilingual user interface on the software side!
Amazfit Watch app
To start up the smartwatch, you need the Amazfit Watch app, which is available for both Android and iOS mobile devices. A disadvantage of the Chinese Stratos is that the Amazfit Watch app available in the respective app stores in this country does not yet support the Chinese Amazfit Smartwatch 2. You can find a link to the Chinese Amazfit app here: app.mi.com
The app itself adapts to the system language and is completely available in English on a smartphone with the German language setting. A Mi account is required to use the app. The connection between the app and the smartwatch is via Bluetooth. A QR code with the connection data, which is displayed on the smartwatch and read out via the Amazfit Watch app, makes it easier to establish a connection.
Flashing Custom ROM? Here the instructions!
Update: Resourceful developers have now released multilingual custom ROMs. The so-called “StratOS” ROM and the “STRATOSfied” ROM translate the user interface into German, English and other languages. The following steps are necessary for flashing.
- Download and install the ADB and Fastboot drivers. You can find generally valid drivers on the net.
- Connect the smartwatch to the PC. Open the Windows command prompt (CMD) and go to the ADB folder with "cd". By entering “adb devices” you can see whether the Smartwatch has been correctly recognized. With "adb reboot bootloader" you switch to the fastboot mode. Then enter "fastboot getvar all" to read out all parameters. Save the parameters for the next step.
- Visit the page unlockamazfit.com and follow the steps there to unlock the bootloader. You have to enter some of the parameters previously called up on the page. Now wait until you receive an email with a corresponding unlock code. In the Windows command line and with the Fastboot mode active, enter "fastboot oem unlock" followed by your unlock code. With "fastboot getvar unlocked" you can check whether your bootloader is unlocked.
- Load the STRATOSfied (Link) or StratOS ROM (Link) down. After downloading, unzip all the files from the ROM you have chosen to your ADB directory.
- For StratOS: Double-click the “Install.bat” to start the installation process. The process usually takes 8 to 10 minutes. The smartwatch must remain connected to the PC! Once started, the smartwatch defaults to Italian. Within the settings you can also select English as the system language.
- For STRATOSfied: If you have decided on STRATOSfied, you have to use “adb push” to copy all files into the sdcard directory of your smartwatch. With "adb root" you switch to root mode. Then switch to a root shell with “adb shell”. Enter "cd /sdcard/; sh start_update.sh" to start the installation process.
Features of the Amazfit Smartwatch 2
After we have dealt with the hardware, let's take a closer look at the range of functions of the smartwatch. In contrast to many other China smartwatches, which are mostly equipped with a native Android and thus allow the installation of further apps, the system of all Amazfit watches is largely closed.
What You See Is What You Get - ie all "apps" or functions are permanently integrated into the system. Nevertheless, the Amazfit user interface offers all the necessary sports and everyday features to make the Amazfit Stratos an everyday companion. The structure of the user interface is clear, even if you must first familiarize yourself with the numerous functions and setting options at the beginning. The performance of the user interface is acceptable. Smaller hangers or less fluent animations are possible!
Pedometer and sports activities
The Amazfit Smartwatch 2 cleverly combines the design of an everyday wristwatch with the functions of a sports wearable. Of course, the numerous sports functions, which, among other things, collect a wide variety of user data in combination with a step counter, a heart rate sensor and GPS, are essential. You can choose from a total of 11 different activities. Here is an overview:
- Running (outdoor)
- Walking (Outdoor)
- Cycling
- Swimming (swimming pool)
- Swimming (open water)
- Running (indoor)
- Cycling (indoor)
- elliptical trainer
- Mountaineering
- Trail Running
- Triathlon
Training modes
Every sport activity offers different training modes and setting options. Among other things, training units recommended by the watch can be started, and you can also create your own training units within the Amazfit app. Training goals per unit can be specified in distance, calories, time or training effect (TE). The different setting options are characterized by the fact that a pool length can be specified for swimming activities, for example, or that geodata can be imported as GPX for walking and running activities in order to be able to walk a specified route.
GPS and outdoor sports
If you start an outdoor sports activity, the smartwatch first tries to find a GPS fix. This enables even more precise data acquisition. However, if you opted for the Chinese model of the Amazfit Stratos, the watch lacks the European map data. In the evaluation you get the route, but there is no map display (see screenshot)! As soon as the smartwatch can also be connected to the international Amazfit app, the corresponding map data will most likely be submitted later.
Pedometer
In addition to sports activities, the smartwatch also records everyday movement. The daily steps are counted by means of a step counter. A daily goal can be set individually. The distance covered and the calories burned are also determined from the steps. The step counter is convincing in practice. The step recognition is precise. Incorrect measurements due to driving a car or other activities that do not represent a step movement do not occur.
Heart rate sensor and sleep monitor
A combination of photo diode and LED is located on the underside of the smartwatch for heart rate measurement. The sensor measures the blood flow under the skin, which reflects the current heart rate. In addition to a single measurement, an interval measurement and a continuous measurement are also possible. The accuracy of an optical heart rate measurement must always be viewed critically.
In the test, the measurement accuracy of the heart rate sensor was less convincing. A precise heartbeat rate is measured when the patient is idle, but the results are significantly different when the patient is under heavy strain. To what extent Huami will take care of this measurement inaccuracy remains to be seen. Other users report similar problems. The smartwatch can also be connected to a heart rate chest strap for greater measurement accuracy!
The sleep monitor of the Amazfit Smartwatch 2 is activated automatically and cannot be adjusted manually. Among other things, data on falling asleep and waking up times and the different phases of sleep are collected. The detection of the individual sleep times worked quite well in the test. It takes getting used to, however, to go to sleep with a rather large wristwatch.
Weather features and GPS
To keep up to date with the weather, the user interface offers a 5-day weather forecast. The respective location and the temperature unit can be adjusted in the Amazfit app. The current weather is displayed with maximum and minimum temperatures.
As mentioned before, the watch is also equipped with a GPS module. The watch finds a GPS fix quite quickly. An e-compass, which is also available, enables precise reproduction of the cardinal direction. The Amazfit Stratos provides other and also plausible measurement data for air pressure and altitude above sea level, among other things.
Music, alarm clock and training plan
With the integrated music player, the smartwatch can also be used to play music. Almost 2.56GB of remaining memory is available for this, which is regularly sufficient for 500 songs. Connected to a PC, music tracks can be copied to the memory of the smartwatch and played via connected Bluetooth headphones. There is no radio function!
The alarm function is comparable to the alarm clock on a smartphone. Different profiles can be created and there is also a snooze function. A vibration of the Smartwatch represents the alarm. The vibration strength can be set in 3 levels (soft, mild, strong). There is no smart wake-up function that automatically wakes you up based on the sleep phase.
The "Training plan" mode offers 5 different training plans for beginners and professionals over several weeks (56 days). If you activate a training plan, you receive daily guidelines for physical activity.
Stopwatch, timer and Mi Home
A classic stop function with split time display is also available as an app. Individual or specified periods of time can be measured using a timer. "Mi Home" is also integrated, which can be used to control various products of the Xiaomi ecosystem (e.g. lamps).
Push notifications, screen unlock and others
The smartwatch is able to receive push notifications from a mobile device connected via Bluetooth. For example, if you receive an app notification (WhatsApp or Facebook, a call or an SMS), you will be notified directly via the watch. The notification content (text + emojis), including multiple messages, is displayed legibly. There is no way to answer directly via the smartwatch! Which app is allowed to send notifications to the watch can be set within the Amazfit app.
The screen unlock function allows the smartwatch to be used as a secure unlocking device. The Stratos can be set up as a trustworthy Bluetooth device within the security settings of the mobile device. If you are now in the vicinity of the mobile device as a watch wearer, no PIN, pattern or password is required to unlock.
The smartwatch receives official updates via the integrated WiFi module. For travelers, the watch offers a flight mode so that the Amazfit Smartwatch 2 can also be used on the plane.
Amazfit Watch app
The management of the smartwatch and the data it collects takes place via the Amazfit app. The start screen provides information on the current number of steps, the battery, heart rate and sleep.
Sports summary
The "Sport" tab takes you to the sport overview. Here the tracked sports activities can be displayed with information on the duration, the average heart rate, the distance covered, the steps and the calories burned. The sports activities can be filtered according to days, weeks and months, as well as according to the respective activity. If you click on a sport activity, you get a detailed overview of the respective measurement data.
Profile
Smartwatch and app settings can be made via the "Me" tab, and personal VO2max and EPOC parameters can be called up. The widget arrangement, for example, can be adjusted in the settings. In addition, there are setting options for real-time data recording of individual sports activities, as well as weather and notification settings can be made. With the help of an integrated file manager, you have access to the clock's file system.
Watch Faces
Watchfaces can be downloaded from a store that is also integrated in the app. However, the store didn't really work in the test. Alternatively, you can choose from 14 pre-installed digital and analog watch faces. The background images of individual watch faces can be exchanged for your own images. Own watch faces can be uploaded in the .wfz format.
Overall, the app is clearly structured and offers numerous management and setting options. A synchronization with Strava is not yet possible with the Chinese Stratos Smartwatch, as the Chinese Amazfit app, unlike its international counterpart, does not allow external synchronization of the data. However, synchronization with the Mi Fit app is supported!
Battery
The capacity of the battery is given by Huami as 280 mAh, which also corresponds to the measured value. The running time should be around 30 days with daily physical activity of 5 minutes and constant receipt of push notifications. With active GPS and automatic heart rate recording, the running time is reduced to 35 hours (information according to Huami).
In practice, the Stratos will run for around 3 days. This value results from an activated heart rate measurement, a regular receipt of notifications and a daily 45 minute sports program with activated GPS. The smartwatch is connected to the 4-pin charging station for charging. In the test, the charging station proved to be stiff, which is why the smartwatch had to be literally pressed into the dock. A full battery charge takes 2 hours.
Review
Huami is a company founded in 2014 that specializes in smart wearables and is now one of the world's largest wearable manufacturers. Huami was best known as the producer of the Xiaomi Mi Band 2 and also other Xiaomi wearables, most of which are produced by Huami and distributed by Xiaomi. The manufacturer has its own range of products under the name “Amazfit”, which is characterized by well-equipped and high quality smartbands and smartwatches. The Amazfit Pace was the first Huami smartwatch that we also tested and was convincing by the transflective display, the lush functionality and the long lasting battery life. Other Huami wearables of the last months are the Amazfit Bip , a low-cost alternative to Amazfit Pace , as well as the Mi Band Alternative Amazfit Arc .
Amazfit Sport Smartwatch 2 / 2S (China) Amazfit Stratos (Global)
Everyday design
Good workmanship
IP68 water protection
Extensive sports functions
GPS, WiFi and Bluetooth
Transflective display
Accurate pedometer
Comprehensive app
Numerous watch faces
Acceptable battery life
Watch band with fast wear
Heart rate measurement in need of improvement
Minor performance drops
The Huami Amazfit Smartwatch 2 is one of the most functionally comprehensive sports wearables on the market. With a total of 11 different sports activities and many individual settings options, the smartwatch is versatile. The pedometer impresses with its precise step detection. The accuracy of the heart rate measurement, however, is in need of improvement.
Even as an everyday clock, the Amazfit Stratos makes a good figure. Huami cleverly combines a sporty and elegant watch design. Through the transflective "always-on" display, the clock is readable at any time. Various and self-created Watchfaces provide more variety.
In direct comparison to the Amazfit Pace, however, the Amazfit Stratos is much more of a design upgrade. The hardware has remained identical to its predecessor and there are only a few new features on the software side. For the Amazfit Stratos, however, clearly the IP68 water protection speaks, which is why the Stratos is also suitable for swimming.
reyni
6. December 2017 14 to: 41
Hopefully that comes with Android Wear.
Timo admin
7. December 2017 18 to: 21
That is rather unlikely, although the first China smartwatches with Android Wear have recently appeared (see Ticwatch S&E). But on the 12th we will know more for sure;).
Bernd
12. December 2017 15 to: 26
So is that just a pace in a different design? I would have liked to have upgraded the hardware. Somehow disappointing, but I like the design better than the pace. I'll stick with my old one for now and then switch to this one as soon as I can do something with the firmware.
Regards
Timo admin
12. December 2017 15 to: 49
Hi Bernd, yes, the new Amazfit Smartwatch is more of a design and software upgrade. I'm also curious to see what will be possible with the new firmware and to what extent the Amazfit App 2.0 will differ from its predecessor.
jens
12. December 2017 20 to: 57
Hi Timo, I really liked your pace test. Are you going to test the new one too? I ask because I'll order this one next year and give the old one to my wife 😛
Timo admin
13. December 2017 20 to: 22
Hi Jens, of course, as soon as the smartwatch is available, I'll try to get a copy. But it will very likely not be until February before the review goes online.
Thomas
21. December 2017 10 to: 35
How exactly do you use the Stratos? Does it have a bezel like the Samsung Watch or how can I imagine that?
Timo admin
10. March 2018 18 to: 44
Hi Thomas, the smartwatch is operated purely via the display and the control buttons on the side.
Marcel
10. March 2018 18 to: 13
Does the Huami Amazfit 2 (Stratos) have a built-in microphone or speaker? (Even if there is no software available at the moment)
Timo admin
10. March 2018 18 to: 43
Hi Marcel, you can take a look at the inner workings of the watch at the following link: https://fccid.io/2AC8UA1619/Internal-Photos/Internal-Photos-3750819
I couldn't make out a hidden speaker or microphone (as is the case with Pace!).
Heike
21. March 2018 15 to: 28
Are you 100% sure that I can connect the Stratos to an external heart rate chest strap (or even to the PolarOH1 = pulse sensor) via Bluetooth LE? And how does it work. Do I have to first call up a sport function and then pair it? Thanks in advance.
Timo admin
21. March 2018 17 to: 49
Hi Heike, if you select a sports program and go to Settings, you can add "Accessories". I don't know whether every chest strap is supported. At least it worked with a Wahoo chest strap. According to the manufacturer, the only requirement is that the strap supports Bluetooth.
Heike
21. March 2018 20 to: 05
Hi Timo. Merci for the super fast answer.
Thorsten
31. March 2018 08 to: 27
can i import a gpx file and use it to navigate when recording the training? can the recorded training data be exported, if so in which data format and is the heart rate included?
Timo admin
1. April 2018 11 to: 08
Hi Thorsten, yes you can import GPX files by connecting the clock to the PC and copying the GPX file into the “gpxdata” folder. The route is displayed on the watch and you can then walk it depending on the sporting activity. Exporting routes as GPX also works. The heart rate is included.
Thorsten
3. April 2018 19 to: 42
Thanks for the detailed answer, but I still have one question. Does the watch also have an auto stop function which can be switched on and off?
Kidney
14. April 2018 23 to: 47
I have to ask the following questions. Is the watch CE certified so that there are no problems with the importation of customs. The watch is available on the well-known sites at good prices and interests me. However, I am somewhat afraid that I will simply throw it in the sand at a cost of 140-160 euros. Unfortunately I cannot find any direct information about the certification for this watch. Do you have the opportunity to give me a little more information. Best regards
Timo admin
17. April 2018 22 to: 01
Hi Rene, the Chinese model does not have a CE mark. The variant sold as “International” has a CE mark on the packaging and directly on the back of the watch.
Julia
11. September 2018 00 to: 38
Hello, does that mean that if I buy the English version via Gearbest, I don't have to pay any taxes?
Michael
19. April 2018 19 to: 28
Hi how is it when I have Spotify on my cell phone, can I control it with the watch? What if I already have bluetooth headphones on my phone? Then the clock is inoperative?
Guido
20. June 2018 17 to: 44
I've been wearing the STRATOS 2 (US version) for 1 week and I'm very satisfied. The daily training for running, cycling and swimming are precisely recorded and all data can be accessed and edited in STRAVA.
At the start of an activity, the GPS quickly finds a signal and the route recording is much more accurate than, for example, with an iPhone 7!
In my opinion, the battery life for a sports watch is outstanding: with 24-hour heart rate measurement, approx. 2-3 hours of training (running and swimming) with GPS and nighttime sleep tracker, the battery lasts for approx. 36 hours until I switch off.
All messages are signaled during the day and phone calls are signaled with pleasant vibrations.
While running, I pair a Bluetooth headset and occasionally an HF sensor - both work reliably and without any problems.
The operation of the STRATOS 2 is intuitive and, thanks to the very precise touchscreen, much more pleasant than with a Garmin Fenix.
And the significantly lower weight compared to Garmin makes the STRATOS 2 the ideal training device for me.
I can't confirm the often lamented wear and tear on the bracelet, which would be questionable after 1 week.
Timo admin
20. June 2018 17 to: 54
Hi Guido, thank you very much for your review.
Lewis
11. September 2018 15 to: 56
Altimeter; does it work when mountain biking and does it count the height ridden (one deduction for descents) Thank you very much
Jenny
28. September 2018 22 to: 54
Hi Timo, thanks for the detailed review. I really like the Amazfit Stratos, which is why I count the watch among my current favorites. But I still have a few questions. I hope you can help me with my decision.
1. I read something from a Stratos more often. 2. Are there different models of the watch or already a successor?
2. Can the watch strap be exchanged easily?
3. Really waterproof?
4. Can I also use the Stratos to listen to music?
That's it for now. Would be great to hear from you.
LG Jenny
Timo admin
29. September 2018 13 to: 29
Hi Jenny, I am happy to answer your questions.
1. There is no Stratos 2. In China, the watch was released as "Amazfit Sport Smartwatch 2". Some less well researched sites simply mix both names, which is why such misinformation arises.
2. Yes, you can easily change the watch strap. The bracelet is attached with a pin clasp.
3. I take a shower and swim with my Stratos. Salt water and diving should be avoided.
4. The clock has an internal memory (approx. 2.5 GB) on which you can store some MP3s. You can also connect Bluetooth headphones to the watch.
I hope I could help you with your decision 🙂
ivffff
6. February 2019 16 to: 35
Ahoy,
what is the difference between the model numbers A1619 and P182 on the Stratos? Does anyone know?
eric
25. May 2019 12 to: 14
als he nu is een nederlandse handleiding bij was he was het beter
Bernd
14. June 2019 14 to: 05
Hello Timo, nice report about the watch, which I recently called my own 🙂
Perhaps you can answer the following question for me: I let the alarm wake me up every day with the watch on my arm, but this only works to a limited extent. In the meantime I have found that the watch should actually vibrate for up to 5 minutes if you don't press snooze or stop.
And now what I can't explain to myself: If the watch starts to vibrate, it does it exactly once 🙁 I tested it once and set a test alarm. As soon as you touch the display with anything (blanket, etc.) the alarm goes off. The awakening is of course not successful 🙁
Do you have a tip ?
AndiM
22. February 2020 10 to: 26
The enclosed instruction manual is a joke, it briefly explains in English how to (forcibly) register, that's all. Otherwise you have to look at the operating instructions (also only in English) on the PC. Snapping the watch into the charging cradle is a fiddly job.
The operation is confusing and unintuitive. In addition, the display reacts poorly to taps. For example, if you want to end a sporting activity you keep tapping on the display and don't know whether the watch reacts so slowly or has not registered the pressure at all, I had the impression that this behavior was even worse at low temperatures (outdoor sports in winter) will.
The stopwatch can only be reset via the display and then type around the display for a long time until the key press is registered. Why is that not possible via one of the push buttons?
After loading and updating, the first sporting activity, one hour of cycling. The watch cannot find a GPS signal at all, tried again and again, i.e. started without GPS. The heart rate display is completely wrong, shows values around 60, while the chest band shows twice as much.
Still no GPS after many attempts over the next few days. Only after another update does it suddenly work - with modest accuracy.
The display looks a bit pale and colorless. In addition to the supplied watch faces, there are thousands more available for download online, I didn't really like any because unnecessary things (calories) are always displayed and others that one would like to have are missing. (I would like to have the time digitally, with seconds and German date format, pulse, steps ...).
The stairs are the least accurate of all the measured values, as the displayed value is 5 - 10 too low.
Synchronization with the smartphone via Bluetooth runs smoothly. It would be nice if you could also transfer your training and measurements to the PC, maybe even work, but I haven't found it.
Yesterday the watch didn't record any sleep data, no idea why, let's see if it works again today.
The running time with permanent heart rate measurement and one hour of training with GPS is about 3 days, pretty little compared to the manufacturer's information.