Smith & Wesson K frame mainspring $15.00 Part 88 on the exploded diagram. Used, excellent condition mainspring from a 19-4, K frame revolver. Will fit other models of K frame revolvers. Out of stock Category: Smith & Wesson Related products Smith & Wesson J Frame Rimfire Shooters Pack $19.97 Smith & Wesson K frame thumb piece early style, blue $35.00