Crimson Trace LG-359 Lasergrips Red Laser Sight Grips for Smith & Wesson 3rd Generation Pistols POWERFUL RED LASER: Features a 5mW peak, 620-670nm, Class 3R visible red laser - the brighest beam allowed by law. INSTINCTIVE ACTIVATION: Dual side activation buttons engage 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 3rd generation, full size, double stack EASY INSTALLATION: User installed- no gunsmithing required. Factory sighted at 50 feet, but is fully user adjustable for Windage and Elevation with provided tool. This model features a master ON/OFF switch for completely powering down the unit.