By utilizing Pos-Align Offset Inserts in Signature Rings, you can virtually sight-in your gun without moving the scope adjustments. By keeping the internal optics centered, you'll see through the scope all of the clarity, sharpness, and brightness that the optics designers intended for you to see. 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. And for you 1000-yard shooters, the need for expensive tapered bases or shimming becomes a hassle and expense of the past. Kit inlcudes one set of each .005, .010, .020. Mfg: Burris SPECS: Synthetic, black. For 1" rings only. Kit includes: .005, .010, .020 inserts.