This app is an Android Wear OS companion app for Xiaomi Mi Band 4. You can use the app to set any watch face that you want, including the most popular ones such as the simple watch face, the digital clock, the calendar, the stopwatch, and more. The app is free to use, and you can set any watch face without the need to root your device. It is compatible with all devices that use the Android Wear OS. The watch faces are all free and can be downloaded and installed on your device. You will not need to install the Android Wear OS on your device.