Wilson's Custom-Tune Spring Kit is designed to easily and inexpensively improve your revolvers' action and functionability. It features the finest gun springs available, made from high-tensile spring wire, for the finest possible action tuning jobs. The springs lightens the trigger pull on single action revolvers and improve the single and double action trigger pull on double action revolvers. This model is compatible with S&W J frame and includes a No. 8 reduced power hammer spring and No. 13, 14, 15 reduced power rebound trigger spring.