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 2 hours of run time with (4) included 2016 Lithium Batteries.