Smith & Wesson K frame thumb piece nut, blue $10.00 Part 21 on the exploded diagram. Used, excellent condition blue thumb piece nut from a 19-4, K frame revolver. Will fit other models of K frame revolvers. Only 1 left in stock Smith & Wesson K frame thumb piece nut, blue quantity Add to cart Category: Smith & Wesson Related products S&W 59/459/5904 series XP magazine springs 3 pak $34.97 Smith & Wesson M&P 9mm .40/.357 Recoil Spring 19lb. $14.97