Ultimate Arms Gear Black Recoil Impact Cushion Shock Absorber For Glock Pistol Models : 17, 17L, 18, 19, 20, 21, 22, 23, 24, 24C, 31, 32, and 37 Polyurethane shock absorber cushions the impact and absorbs the shock against the polymer frame, resulting in less wear to the gun, less fatigue on the hand and arm, and less muzzle rise. Allows you to get back on target quickly for faster, more accurate follow-up shots Each absorber is precision CNC cut from a sheet of ultra-tough, tear-resistant polyurethane. Drop-in installation without any permanent alteration to the firearm Will fit models 17, 17L, 18, 19, 20, 21, 22, 23, 24, 24C, 31, 32, and 37. It will not fit Generation 4 Glocks. Rated to last up to 1000 rounds of repeated firings and is easily replaceable.