Anthias (Asus Zenwatch) is a medium-sized rectangular watch released in 2014.
Anthias is a slim watch with a steel front casing. The front glass curves slightly, feeling slimmer than many other watches and the 320px OLED display has rounded corners. The side of the case has a rose gold/copper coloured inlay. There are no easily accessible buttons on the watch, so most interaction is done through the touchscreen. The front of the watch hides an electronic heartrate sensor. Anthias takes standard 22mm straps.
The back of the watch is held on by 4 Torx T5 screws, and water resistance is achieved with a gasket, so repairs are easy. Parts are available. You will likely need to replace the battery when buying these watches as they are getting quite old.
Miscellaneous hardware docs
The power key on anthias is on the back, which means that it's used more like a reset button for emergencies. The key is exactly the same as the main power button on any other watch.
Manually getting to fastboot
During the first seconds of the boot process, swipe diagonally across the screen. Starting from the top/left outer edge of the screen to the bottom/right.