LG-637G Green Lasergrips are a rear-activated green laser sight compatible with GLOCK Full-Size Gen 3-17/17L/22/24/31/34/35/37 Gen 4-17/22/31/34/35/37 Gen 5-17/19/19X/45. Featuring Crimson Trace’s famed Instinctive Activation, which allows the laser to be activated with a normal firing grip, the LG-637G includes a Master On/Off Switch for completely powering down the unit. User-installed in moments by attaching securely to the gun frame, this laser sight is fully adjustable for windage and elevation. Provides 2 hours of run time with (4) included 2016 Lithium Batteries.