The Vortex Viper Cantilever Mount is designed to mount optics with an AR-15 flattop receiver. The cantilever ring mount positions the center of the riflescope tube at a height of 1.435" form the base. The superior clamping surface area provides a sure hold on Picatinny-style rail that may even be somewhat out of spec. The mount is CNC machined from solid 6061-T6 aluminum and features a hard coat Type 3 Mil-spec anodizing for a lifelong lasting finish. Notes:Height: 1.435." (measured from top of rail to center of scope tube)Mounting hardware included