Leupold 1 Inch Medium Standard Rings, Matte Black - 49901 - Strike forged steel for a 28% strength improvement. - Anti-slip groves, no lapping required. - CNC machined for perfect alignment. - Locking screws with nylon so they will not back out under recoil or vibration. - Engineered to match up with STD one-piece and two-piece bases.