NcStar 30Mm Cantilever Ring Mount/Weaver Style. The NcStar 30mm Cantilever Ring Mount Weaver Style fits well with 30mm or 1 inch scopes and reflex optic and mounts securely to your firearm with the slotted thumb nuts. Specifications for NcStar 30mm Cantilever Ring Mount Weaver Style: Manufacturer: NcSTAR Finish: Matte Tube Diameter: 30 mm Ring Quantity: Single Mount Type: Weaver Gun Rail: Weaver Features of NcStar 30mm Cantilever Ring Mount Weaver Style: Works with 30mm or 1 inch Scopes and Reflex Optics Mount height is at the AR15 height for Co-Witnessing with your Iron Sights Mounts securely to your firearm with the Slotted Thumb Nut All Aluminum Construction Package Contents: NcStar 30mm Cantilever Optic Mount NcStar 30Mm Cantilever Ring Mount/Weaver Style MDC30