The LG-313 "Hoghunter" LaserGrips are designed especially to fit Smith & Wesson N Frame revolvers with a square butt, while offering the latest Crimson Trace designs for comfort and battery life. *(Grips/Laser only, gun not included).Specifications:- Activation: Instinctive Activation; Front- Materials: Rubber Overmold- User Adjustable: Both Windage and Elevation - Warranty: 3 Years Complete - Master On/Off Switch: Yes- Beam Intensity: 5mw peak, 633nm, class IIIa laser. Maximum output that federal law and technology allow. - Dot Size: Approximately 0.5" diameter at 50 feet. - Power Source: Two #2032 lithium batteries (included); over four hours of on-time use and a five year shelf life - Fits: N Frames square-butt only... Models 21, 24, 25, 27, 28, 29, 57, 58, 520, 624, 625, and 629.