These are replacement inner and outer recoil springs for Colt 1911 pistols chambered in 9mm Luger that use the new Colt Dual Spring Recoil System(TM) originally developed in 2011 for the USMC M45A1 pistol. The inner and outer springs work together to provide enhanced reliability and extended recoil spring service life up to 15,000 rounds. (The standard interval for replacing standard 1911 recoil springs is 5,000 rounds.) This longer service life is particularly helpful to high-volume shooters who shoot their pistols A LOT, military and law enforcement personnel, as well as competition shooters. Other benefits of the dual recoil spring system are a gentler recoil impulse (which aid Mfg: Colt
