The Midwest Industries QD 1" Scope Mount is precision machined for optimum return to zero performance and reliability. The extremely smooth operation with a multi-facetted adjustment nut to get the exact tension required by the operator. The mount is fully adjustable with no tools required and can be adjusted to fit rails not machined to mil-spec tolerances. Made of hard coat 6061 aluminum it is sure to last you a lifetime. Backed by Midwest Industries Lifetime Warranty. Additional Specifications:Width of rings: 0.85"Distance between rings: 2.80"Offset from the first ring: 1.40"Height: 1.41" from top of rail to center line of ring FeaturesSuperior clamping that will not damage or coin the rail surfaceFully adjustable with no toolsPatented Quick Detachment leverLifetime warranty