Wilson Combat's Custom Tune Spring kit for 45 ACP, 1911 full size contain the finest gun springs available, made from high tensile spring wire for reliable function, smooth operation, consistency and long life. 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 and extra power firing pin spring- increased firing pin tension for longer life and enhanced safety should the pistol be dropped.