Scope Base Rail Mount Picatinny Weaver for Ruger Mark II 1 2 3 4 IV 22/45 Pistol, Anodized Black Features: This is a scope base rail mount in black anodized finish for use on Ruger Mark I, II, III, 1 2 3 IV 22/45 22LR pistols with factory drilled holes. Machined from extruded aluminum alloy, the mount has 11 more up-to-date Picatinny-style ring slot cuts, which give more choices of placement of Picatinny or weaver scope rings on the rail. It is also good for use to install the popular mini red dot sight, which typically has picatinny recoil lug built in. This rail can be mounted with a rear sight in place. Finish is anodized matte black. Rail Type: Weaver with Picatinny-sized ring slots Number of ring slots: 11 Overall length: 4 1/2 Weight: 1.2oz Package contents: 1x Scope Base Rail Mount 4x Mounting Screws 1x L wrench