The XTR Signature Rings were designed for the tactical shooter. They deliver plenty of holding power, with less weight. Unique, self-centering, dual steel clamps with full cross-through connection assure proper center on any width Picatinny rail, while adding extra strengthRevolutionary Pos-Align® Inserts technology, in a tactical ring configurationPos-Align Inserts guarantee perfect centering and maximum scope-to-ring contact for tremendous gripping power without damaging the scope finishLets you virtually sight in your gun without moving the scope adjustmentsCorrects misalignment caused by off-center receiver holesCorrects for bases or rings being slightly off-centerNo need for expensive tapered bases or shimming for thousand-yard shootingRugged, robust aluminum tactical rings save weight and mount on any Picatinny and most Weaver style railsEach ring set includes one set of the +/- 0 MOA concentric, one set each of the +/-5 MOA and +/-10 MOA, and two sets of the +/-20 MOA. With these inserts, it is possible to make 0, 5, 10, 15, 20, 25, 30 or 40 MOA of cant in the scope mount. This pair of 30mm Burris Xtreme Tactical scope rings has a height of 1.5" and fits picatinny style rails. Burris Xtreme Tactical 30mm 1.5" Rings 420223