Crimson Trace LG-852 Lasergrips Red Laser Sight Grips for GLOCK Gen4 Subcompact Pistols 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. OVER FOUR HOURS OF BATTERY LIFE: Powered by two #2025 Batteries (included). This product is eligible for Crimson Traces Free Batteries For Life Program. FITS: Glock GEN4 26, 27, 33 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. Rear activated laser Minimal size laser diode for compactness Utilizes CR2025 batteries for a sleek design and ultimate fit to the grip and the shooters hand Adjustable Windage and Elevation Class IIIR Laser Product: &lt;5mW power output