AR15 M4 Cantilever 30mm / 1" Quick Release Offset Scope MountWorks with both 30mm and 1 inch scopes Heavy duty, single unit base, machined from aircraft grade aluminum alloy Offset design for better eye relief position 6 bolt for each ring to secure, shock proof Built in Weaver style rails very handy fitting flashlights and lasers etc. Ring size: 30mm 1 (with insert included) Height from rail to scope ring center: 1. 38 inch Mounting bolt distance: 50mm (1. 97 inches) Distance between inside edge of rings: 2. 1