Wolff Gunsprings engineered specifically for Smith & Wesson revolvers across J, K, L, and N frame models. Compatible with numerous variants including J-frame (31, 32, 34, 36, 37, 38, 42, 442, 49, 60, 63, 631, 632, 637, 638, 640, 642, 649, 940), K-frame (10-19, 65-67, 617, 648), L-frame (581, 586, 681, 686, 696), and N-frame (24-29, 57, 610, 624, 625, 627, 629, 657). This Reduced Power 13LB Rebound Spring (Part# 16662) delivers precision performance in a single-unit package.