Crimson Trace LG-105 Lasergrips Red Laser Sight Grips for Smith & Wesson J-Frame (Round Butt) Revolvers POWERFUL RED LASER: Features a 5mW peak, 620-670nm, Class 3R visible red laser - the brighest beam allowed by law. INSTINCTIVE ACTIVATION: Front activation button engages the laser immediately when the firearm is held in a normal firing grip. This is the feature that sets Crimson Trace apart from the rest. OVER FOUR HOURS OF BATTERY LIFE: Powered by two #2032 Batteries (included). This product is eligible for Crimson Traces Free Batteries For Life Program. FITS Smith & Wesson J-Frame Round Butt EASY INSTALLATION: User installed- no gunsmithing required. Factory sighted at 50 feet, but is fully user adjustable for Windage and Elevation with provided tool. Laser grip designed for Smith & Wesson J-Frame round-butt revolver line Instinctive front activation; fully adjustable for windage and elevation No gunsmithing or frame modifications required for installation Grip replacement attachment; hard polymer and rubber construction Runs on pair of 2032 lithium batteries; 3-year warranty