LG-637 Lasergrips® are a rear-activated laser sight for GLOCK Full-Size pistols (Third Generation 17″ 17L” 22″ 24″ 31″ 34″ 35″ 37″ Gen4 17″ 22″ 31″ 34″ 35″ 37 and Gen5 17″ 19X” 45). Featuring Crimson Trace’s famed Instinctive Activation™” which allows the laser to be activated with a normal firing grip” the LG-637 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 (2) included 2032 Lithium Batteries.