These watch faces are available for all Samsung Galaxy smartwatches. Some are also available for Apple Watches and Wear devices.
You can download watch faces directly from the Galaxy Wearable app, which you need to set up your Samsung Galaxy watch. Watch faces are also available through the Galaxy Store mobile app for iOS and Android. There are a few other apps, like Facer and Watch Maker, that allow you to download additional clock faces for your Samsung device.
Samsung watches use a Linux-based operating system called Tizen. Any Tizen-compatible watch face works with Galaxy smartwatches.