This is a Butler Creek Slip On known as the Recoil Pad, model 50327.
Butler Creek's Slip-On Recoil Pad is ideal for firearms with plastic or metal butt plates. Its convenient slip-on cushioning reduces felt recoil and improves accuracy by minimizing fatigue and flinching. The elastomer material has a leather-like texture and appearance.
Features:
Large slip-on recoil pad (5.30Hx1.72W)
0.75 thick;Ideal for firearms with plastic or metal buttplates