These Crimson Trace Lasergrips fit S&W revolvers and operate using front placement instinctive activation. They have user-adjustable windage and elevation. Two batteries provide more than four hours of on time use. These Lasergrip models feature a hard polymer surface well suited for personal defense or rubber overmold with a polymer base. The smooth polymer material provides for snag-free draws and is hard enough to meet strict standards for durability and reliability. *Note- fits S&W Airlight, Airweight, Bodyguard (except polymer-framed models), Chiefs Special, Centennial, Ladysmith, Models 36, 37, 38, 49, 60, 63, 317, 331, 332, 337, 340, 342, 351, 360, 442, 637, 638, 640, 642, 649, 651 and 940. round butt only.