Description 69541 Wolff Service Pak Glock 17 17L 20 21 22 24 31 34 35 Wolff Service paks Type I for Glock pistols contain the following replacement springs to return the pistols to original factory condition: Wolff recoil spring, striker spring, trigger spring, extractor plunger spring and firing pin block spring.   Please note: The recoil springs included are for use with Wolff guide rods only and not a replacement factory captive recoil spring assembly.   Note: Not for use in Generation 4 pistols.