LG-639G Green Lasergrips are a rear-activated green laser sight for GLOCK Compact pistols (Third Generation 19, 23, 25, 32, 38, Gen4 19, 23, 32, and Gen5 19). Featuring Crimson Trace's famed Instinctive Activation, which allows the laser to be activated with a normal firing grip, the LG-639G 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 4 hours of run time with (4) included 2016 Lithium Batteries..