The Midwest Industries Cantilever QD Ring Mount is one of the smoothest functioning QD lever on the market. Superior clamping that will not damage or coin the rail surface. Extremely smooth in operation with a multi-facetted adjustment nut to get the exact tension required by the operator. Center line height of 1.690 for a lower one third sight picture Fully adjustable with no tools required, can be adjusted to fit rails not machined to mil-spec tolerances Weighs only 4.0 oz. Precision machined for optimum return to zero performance and reliability Hard coat anodized 6061 aluminum for a lifetime of service Patented QD lev Mfg: Midwest Industries