Lasergrips are a rear-activated laser sight featuring Crimson Trace's 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. Includes 2032 Lithium Batteries. *Compatible with Glock Gen3 17/17L/22/24/31/34/35/37, Gen4 17/22/31/34/35/37 and Gen5 17/19X/45.