1" Signature Rings POS-Align Offset Insert Kit by BURRIS OPTICS + and - .005" + and - .010" + and - .020" 6 Total Inserts Only Signature rings will accept the Pos-Align Inserts and a synthetic self-aligning insert that provides 100% scope-to-ring contact and 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. Offset inserts also correct for any misalignment caused by receiver holes drilled off center and or the bases or rings being slightly off perfect center. They keep the internal optics centered to provide all the clarity and sharpness and and brightness that the optics designer intended for you to see.