Please beware of the china made copy by nightsnipe! I’m the original inventor. Mine is made right here in the USA !Black anodized 6061 Aircraft aluminum. Sightmark Wraith HD-4, HD-2, 4K Max, and Mini, extension rail. CNC Machined. This extension rail relocates the factory mount 3 1/2 inches. And can be used with the QD base. Includes mounting screws. All you will need is a good Allen wrench and blue loctite.