Custom-Tune Spring Kits contain the finest gun springs available, made from high tensile spring wire for reliable function, smooth operation, consistency and long life. Full-Size/Government .45 ACP "Custom-Tune" spring kit includes: 10 lb reduced power recoil spring - lighter spring for light practice rounds, heavy-duty for longer life, 18.5 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 - increased firing pin tension for longer life and enhanced safety should the pistol be dropped.A properly tuned 1911 Auto is unquestionably the finest combat pistol in the worldThe first step when tuning your pistol is replacing the stock springs with Wilson "Custom-Tune" SpringsThese springs are produced from the finest high tensile spring steel, assuring a consistently smooth action, positive ignition, and proper timingOnce installed, your pistol will be "Custom-Tuned" for maximum reliability