This is an optical grade Gorilla Glass screen cover for the DM240, DM241 & DM242. The cover's primary function is to prevent damage to the panel, especially from fingers that may poke and prod at the screen. The cover fastens into place securely on the chassis with 4 provided nylon thumb screws. This cover is more impact and scratch resistant than the less expensive clear protective acrylic covers, but slightly more reflective. We suggest pairing this cover with a hood if you plan on using the monitor in a brighter environment.