The LaserMax guide rod laser sights for GLOCK Gen4 pistols give you the additional convenience of a laser sight with no external additions to your weapon. Unlike all other laser sights, the guide rod laser is completely internal and simply replaces the factory guide rod and take down lever. With the guide rod sighting system there is no need to replace holsters, remove tactical lights or grips because the laser sight fits right into your current setup with no gunsmithing required. Not only are these units convenient, but they are reliable and built with high quality material and Wolff Gunsprings, so you know you're getting the best there is. LaserMax guide rod laser have been torture tested to Military and Homeland Security Specs including:Blowing sand tests Salt water corrosion test 5-story drop to concrete Extreme temperatures 2-hour salt water submersion @ 66' 20,000 round live-fire test When you want the added confidence of a pulsating red laser sight, the LaserMax guide ...