American National Firearms accessory kit for Glock Generation 4 models 22, 31, 35, and 37 (G22, G31, G35, G37.) Set includes stainless steel dual-spring recoil guide rod system, extended slide lock and a 4-piece frame pin set. They are all perfect, just like your Glock. This set is for Generation 4 Glock models 22, 31, 35, and 37 only. It will not fit Generation 1, 2 or 3 models. Please do not try to make it fit other generations, it will not fit, and you can not make it fit. It fits the Generation 4 Glock models 22, 31, 35, and 37 only. Lifetime warranty.