Wilson Combat's Custom-Tune Spring Kits are designed to easily and inexpensively improve the action and functionality of your handgun. These quality spring kits feature the finest gun springs available, made from high-tensile spring wire for the finest possible action tuning jobs. Kits include the various springs necessary to assure reliable function, smooth operation, consistency, and long life. Contains Reduced power mainsprings 9, 10 and 12lb and 10 and 12lb reduced power trigger rebound spring.