The LaserMax Guide Rod Laser for Glock meets or exceeds both Mil-Spec and Homeland Security durability test standards (drop tests, blowing sand, temperature and humidity extremes, salt water fog, deep water immersion, 20,000+ rounds live fire). If you can field-strip your Glock, you can install your LaserMax Guide Rod Laser sight—No gunsmithing to your Glock required. A pulsating laser beam gives effortless awareness of muzzle direction, and it transcends language barriers. It can be used outdoors from dusk till dawn, or indoors round-the-clock. Infra-Red versions are optimized for NVG characteristics. The Internal Guide Rod lasers for Glock come permanently aligned from the factory for center-of-mass accuracy at 20 yards, it will never drift out of alignment, and there is no need to re-zero after changing batteries. As close to the bore of the Glock as possible, positioning allows for the closest and most consistent relationship between your point of aim and point of impact (POA/POI) over all shooting distances, especially useful for moving targets. Ambidextrous switch in custom take-down lever that very closely resembles the factory Glock take down lever. Deliberate on/off activation which is highly desirable in a tactical or personal defense situation!