The Ncstar compact pistol green laser sight with KeyMod rail fits most full size and compact framed pistols like glock with 1.7"-2.0" Weaver / Picatinny / MIL-STD 1913 rail. Fully adjustable tactical pistol green laser with windage and elevation. Green Laser: 510nm, Max output less than 5mw, Class IIIa Laser. Button on each side of Laser Body allows 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. Length 2 inches width 1.1 inch.