ISMI recoil springs are wound from flat wire so they are a direct replacement for your factory supplied springs. Manufactured from certified Aerospace specification materials. All springs are heat treated, shot peened and stress relieved for maximum durability. ISMI employs ISO 9002 quality control standards. Includes a 12 month manufactures replacement warranty. Fits Full Size Glock models G17,17L,22,24,31,34,35,37,20,21
The stock full size Glock recoil spring weight is 17lbs
Haven't used the spings yet but service was excellent..
It is very good . And I would like lower than 11 lb.