ISMI RECOIL SPRING 15 LBISMI Recoil Spring 15 Lbs - 9mm/40/357 Model Glocks - Flat coil, factory style recoil rod spring - Most commonly used in 9mm, .40 and .357 model Glocks dictated on the Tech Specs - Best use all around for recoil management in most Glock pison the Tech Specs - Best use all around for recoil management in most Glock pistols withtols with