There are many reasons to use a customized rEvo cover plate on your rEvo rebreather.

On the bench, it'll be easy to recognize which rEvo is yours, underwater you'll be clearly identifiable to your buddy but also by photographers, videographers. It offers a bit of protection, made from plexiglas, it's hard to scratch. They add some bling of course but more importantly allow you to personalize your rEvo rebreather easily.