Custom-Tune Spring Kits for full size 1911/Government 45 ACP contain the finest gun springs available made from high tensile spring wire for reliable function smooth operation consistency and long life.The Spring Kit Includes 10 lb. reduced power recoil spring lighter spring for light practice rounds heavy duty for longer life; 18 1/2 lb. extra power recoil spring increases feeding reliability when shooting factory loads heavy duty for longer life; reduced power mainspring (hammer spring) reduced hammer tension resulting in easier cycling and up to 25% reduced trigger pull; extra power firing pin spring increases firing pin tension for longer life and enhanced safety should the pistol be dropped.