This is a Wilson Combat known as the S&W K, L & N, model 178.
Custom-Tune Spring Kits are designed to easily and inexpensively improve your revolver's action and functionality. 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. When only the best will do" Wilson Combat "Custom-Tune" spring kits are the only choice.
Features:
Reduced Power Hammer Spring
12, 13, & 14 Pound Reduced Power Rebound Trigger Springs