Quick release cantilever scope mount. Quick release mount allows easy mounting or dismounting of optic. The scope ring is design to fit 30mm optics or 1 inch with included inserts. AR-15/M16 Quick Release Weaver Style Cantilever Mount with Detachable Rear Ring Includes Mounting Hardware The�mount rings�are 30mm with 1 inch inserts, and the�Mount Rear Ring�is on a dovetail so you can adjust the spacing for a customized fit. In addition the rear ring is also removable so you can set up your�Red Dot Sight�to co-witness with your�weapon iron sights.� Constructed of hard anodized aluminum with solid steel.