The ISMI Extra Power 11 Coil Magazine Spring is 10% stronger than the GLOCK extra power magazine spring. This spring is intended for use on the following GLOCK magazines: 17, 22, 24, 31, 34, 35 and 37.
PLEASE NOTE: These springs will work with standard capacity magazines only (not limited capacity). Using this spring in a magazine may make loading the magazine to full capacity difficult. Cycling ammo through the magazine is the best way to break the spring in.