Fits current production guns with plastic mainspring housing and stirrup. S.N. 219166 and above use heavier recoil springs than earlier models. Contains (1) 20 lb., FSW recoil spring, plus (1) 24 lb., FSW hammer spring, (1) 18 lb., RP hammer spring and (1) XP firing pin spring. Mfg: Brownells SPECS: RP = Reduced Power, XP = Extra Power, FSW = Factory Standard Weight.