Strike Industries 2 Packs Shock Buffer for Glock 17, 17l, 18, 19, 20, 21, 22, 23, 24, 24c, 31, 32, 37 (Not Compatible with Gen 4) **** FREE shipping when checkout ***** Controllable recoil Longer lifespan between metal slide and polymer frame Decrease of shock to hands which prevents muscle fatigue Increased control for precision Uniquely designed cushion knobs for extra buffer