Feature Super Low Profile, 28 mm / 1.1" From Bottom to Ring Center, Six Screws Per Ring Extremely Accurate w/ Full CNC Machined, 11 mm Dovetail Mount w/ Anti-Retreat Pin What are 0 MOA and 20 MOA? 0 MOA: A 0 MOA mount does not have any built-in elevation. When a scope is mounted on a 0 MOA mount, the optical axis of the scope remains parallel to the barrel of the firearm. This means that the scope&';s reticle is aligned with the bore axis, and no additional upward or downward adjustment is introduced.20 MOA: A 20 MOA mount, on the other hand, has a built-in upward cant or angle of 20 MOA. When a scope is mounted on a 20 MOA mount, the optical axis of the scope is angled slightly upward relative to the bore axis. This introduces additional elevation in the scope&';s point of impact. The purpose of a 20 MOA mount is to provide increased elevation adjustment capability for long-range shooting or compensating for bullet drop at extended distances. Specification Ring Diameter: 30mm Overall Length: 144m / 5.7" Overall Height: 48mm / 1.9" Mount Length: 144mm / 5.7" Ring Width: 45mm / 1.8" Central Height: 28mm / 1.1", bottom to center Ring Length: 26mm / 1.0" Gap Length: 63mm / 2.5" Material: 6061-T6 aluminum alloy Weight: 127g / 4.5oz Mount: 11mm dovetail Finish: Black matte Screws per ring: 6 High-durability aluminum alloy in black matte Do not use over 18 inch / pounds of torque on the scope rings&'; screws Suggest 18 inch / pounds torque force for big nuts when installing the mount on the dovetail rail Adjustable anti-retreat pin designed for hard and rigorous use With hex key and retail package, hex key can be used to fasten the clamp nuts Video