Fred Lam wrote:
Besides, is there any good choice for the watch protector?
You may find it helpful to read reviews on popular online shopping sites before deciding on a protector.
Be aware that some screen protectors cover only the flat part of the display, whereas some thin film-type protectors cover the full screen of Apple Watch (ie including around the edges).
Commonly reported problems with snap-on type protectors include that they may, for example: fall off relatively easily, reduce touch sensitivity, scratch quite easily, trap moisture and/or trap small items of debris (which can then cause scratches on the watch case and/or display).