Crimson Trace LG-303 Lasergrips Red Laser Sight Grips for Ruger SP101 Revolvers POWERFUL RED LASER: Features a 5mW peak, 620-670nm, Class 3R visible red laser - the brightest 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: Ruger SP101 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