Crimson Trace LG-639 Lasergrips Red Laser Sight Grips for GLOCK Compact Pistols 19, 23 etc. POWERFUL RED LASER: Features a 5mW peak, 620-670nm, Class 3R visible red laser - the brighest 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. 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 GlockThird Generation 19, 23, 25, 32, 38. GEN4 19, 23, 32. GEN5 19. 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.