SPEED Airsoft Optic BB Shields are designed with optical clarity, and are capable of surviving the most intense CQB shots. Optic BB Shields have been designed to give the lens of your optic maximum protection in the real Airsoft world, and have been torture tested with thousands of BBs. The tough and durable Optic BB Shield does not crack nor allow a single BB to pass through. Size: For Optics up to 2.5" in height Compatibility: Fits most Standard 20mm Rails Material: Optical Acrylic, CNC Aluminum