Fits Colt 1911 1911A1 1991 Government MK IV Gold Cup Commander (.45 Super .38 and 9mm) Officers .45 cal.. Eliminates slide stop top snap plunger top snap plunger and thumb safety failures caused by a broken plunger tube spring. Fits Colt 1911, 1911A1, 1991, Government, MK IV, Gold Cup, Commander (.45, Super .38 and 9mm), Officers .45 cal., and Delta Elite 10mm.. Wolff Eliminates slide stop and thumb safety failures caused by a broken plunger top snap plunger 100246 top snap plunger tube spring.