This VAPRLSBLKM Ncstar compact pistol blue laser gun sight with strobe fits most Weaver Picatinny MIL-STD 1913 rails, on full size and compact framed pistols and rifles with 1.7"-2.0" accessory rails. Compact pistol blue laser sight is fully adjustable for windage and elevation. Laser has button on each side of laser body to allow the user to turn laser On/Off. Holding the button down while the laser is On, turns the Strobe feature On/Off. The laser features our Patented KEYMOD™ undermount for future KEYMOD™ accessories that can attach to the underside of the laser.