A very solid and heavy duty offset ring mount to install magnified optics scope for easier eye relief setup. Very helpful when mounting a scope with longer eyepiece tube, especially ones with illuminated reticles The QD cam locks can be finger adjusted when needed. With the cam lever at unlock position, pull up and rotate the star wheel on the opposite end of the clamping bolt to adjust Ring Size: 30mm (1inch metal size inserts included) Centerline Height - 40mm Machined from extruded aluminum alloy 6061 Anodized black matte finish Clamp attachment - two finger adjustable quick release cam locks Height from top of rail to bottom of cradle: 1" Overall height 2.50" Overall length 5.30" Inner space between the rings 64mm (2.52inch) Ring width: 16mm(0.63inch) Recoil lug: 2 cross-slot square bolt shafts Includes one extra ring top with accessory rail with 4 ring slots