The OnGlass OG 3.0 MagCover Eyepiece Cover magnets to the ring magnets and keeps your optic lens free of dust, scratches, and weather when you're not shooting. FeaturesSnaps on and off instantly with the same magnets that lock in your phoneShields your eyepiece from dust, debris, and moisture in the fieldPrevents scratches during transportLow-profile design that stays out of your way