Burris XTR Ring Xtreme Tactical 30mm Ring, Xtreme Tactical 30mm Ring The massive strength of a wide 6-screw ring is combined with lightweight yet thick cross section aluminum to provide a reliable return-to-zero ultra strong mounting system for Picatinny-style rails. This 1/2" Xtreme Tactical Ring is ready for the heaviest of scopes, massive recoil, and severe usage., Mfg No: 420163, Manufacturer: Burris