Part # 69391 Wolff for Smith & Wesson Pistol S&W 39, 439, 539, 639, 3904, 3944, 909
Service Pak Type-1 9mm
See below about Service Paks:
TYPE I - For Smith & Wesson semiautomatic pistols contains the following springs to replace weakened or broken springs, returning the pistol to original factory condition: recoil spring, extra power firing pin spring, hammer spring, extractor spring, 2 ejector springs, magazine catch spring, drawbar plunger spring, safety lever plunger spring, slide lock plunger spring, safety lever detent spring and rear sight body plunger spring.