If you own are purchasing an expensive optic for your airsoft gun this is a must have. Getting hit and having an expensive piece of equipment break at the same time is not fun for any airsofter. This rail mounted shield will protect your expensive optics from getting hit by BBs. Two 3mm thick acrylic shields are included, one white and one yellow. The shield easily mounts to all standard Picatinny 1913 and Weaver rails and can be folded down when not in use.