Most tempered glass screen protectors advertise a hardness rating of "9H." Contrary to popular belief, this doesn't refer to the Mohs hardness scale. Rather, this means that a 9H pencil — which use the hardest type of graphite you can have in a pencil — won't scratch the screen under normal conditions. A 9H screen protector will give your Switch's screen an incredible amount of protection. But it won't make the screen invulnerable — scratching the protector with enough force might still leave a mark.