Crimson Trace LG-661 Lasergrips Red Laser Sight Grips for Smith & Wesson M&P Compact Pistols Multiple Materials Made in USA POWERFUL RED LASER: Features a 5mW peak, 620-670nm, Class 3R visible red laser - the brightest beam allowed by law. INSTINCTIVE ACTIVATION: Rear 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. Simple factory backstrap replacement. 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 M&P Compact 9MM, .357 SIG, .40 S&W Does NOT fit M2.0 models 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.