Burris Signature Rings set the standard by which all other scope rings are measured. They are the choice of most gunsmiths and serious shooters who want the utmost in accuracy and precision. These solid steel rings not only provide tremendous gripping power and durability, they guarantee proper alignment and maximum scope-to-ring contact through the use of Burris' patented Pos-Align Inserts system.Only Signature rings will accept the Pos-Align Inserts, a synthetic self-aligning insert that provides 100% scope-to-ring contact, compensates for any misalignment in the receiver or bases and also eliminates the need for canted bases or shimming. Pos-Align Offset Inserts can virtually sight-in your gun without moving the scope adjustments. Long-range shooters rely on the inserts to provide more elevation or windage adjustment. The offset inserts also correct for any misalignment caused by receiver holes drilled off center, or the bases or rings being slightly off perfect center. They keep the internal optics centered to provide all the clarity, sharpness, and brightness that the optics designer intended for you to see.