ISMI RECOIL SPRINGS FOR YOUR GLOCK 19, 23, 32 & 38. ISMI recoil springs are manufactured from certified Aerospace specified materials and ISMI employs ISO 9002 quality control standards. The springs are wound from flat wire, heat treated, shot peened and stress relieved for maximum durability making them the best direct replacement for Glock factory OEM springs. Independent tests reveal ISMI recoil springs have endured an excess of 100,000 compression cycles! We advise you practice routine maintenance and change your recoil spring yearly. *Recoil spring buffers are not recommended. Buffers reduce slide travel which can have an adverse effect of feeding reliability. Buffers can break apart during firing and render the firearm inoperable.