NcSTAR NC Star MDC30, 30mm Cantilevr Ring, Weaver Mount Enhance your flat top AR-15 or tactical rifle with this high grade single cantilever ring mount Extends your optical Eye relief forward creating more Clearance and versatility Works perfectly with 30mm optic sights or 1 inch optic sights using the included inserts Enhance your Flat Top AR-15 or Tactical Rifle with this High Grade Single Cantilever Ring Mount Works Perfectly with 30mm Optic Sights or 1 Inch Optic Sights using the Included Inserts Perfect Height for Co-witnessing your Reflex Sight with your BUIS Secures Easily with the Slotted Thumb Nut to virtually any Picatinny or Weaver Style Rails Constructed of Hard Anodized Aluminum for Maximum Stability of your Optic Sight