Sportsmatch SPM-OP25C 1-Pc Mount w/ 1" Rings, Medium, 9.5-11.5mm Dovetail 1" rings Medium profile Fits 11mm dovetail 4 hex screws/ring secure the scope Vertical scope stop pin (removable) Black matte finish The hex screws on the base let you adjust the base to fit the different width rails found on airguns. The clamp is made to securely fit a range of dovetail widths. Helpful resources: Tips for picking scope mounts