Extreme Tactical Signature Rings 1 Inch 1.00 Inch Height by BURRIS Product Overview: The XTR Signature Rings were designed for the tactical shooter. They deliver plenty of holding power and with less weight. Unique and self-centering and dual steel clamps with full cross-through connection assure proper center on any width Picatinny rail and while adding extra strength Revolutionary Pos-Align® Inserts technology and in a tactical ring configuration Pos-Align Inserts guarantee perfect centering and maximum scope-to-ring contact for tremendous gripping power without damaging the scope finish Features: Lets you virtually sight in your gun without moving the scope adjustments Corrects misalignment caused by off-center receiver holes Corrects for bases or rings being slightly off-center No need for expensive tapered bases or shimming for thousand-yard shooting Rugged and robust aluminum tactical rings save weight and mount on any Picatinny and most Weaver style rails Each ring set includes one set of the +/- 0 MOA concentric and one set each of the +/-5 MOA and +/-10 MOA and and two sets of the +/-20 MOA. With these inserts and it is possible to make 0 and 5 and 10 and 15 and 20 and 25 and 30 or 40 MOA of cant in the scope mount.