Double hex screws to hold your scope firmly in place 9-11mm models are fitted with a recoil stop pin Reversible dove tail clamp that fits 9-11mm and 3/8 inch Internal cushion tape prevents marking and damage High-grade aluminium anodized in matte black Details : Configuration: 1 Piece Ring Size (Diameter): 30mm / 1.2 Height: High Rail: 9-11mm Fixings (Rail & Top Cap): Double Hex Screw Internal Cushion: YES Retractable 'Recoil Stop' Pin: YES Height: 50mm / 1.9 Weight: 173g / 6.1oz