The Viridian Reactor R5-R Gen 2 red laser sighting system for the Glock 42. This laser sight is easy to install and blends seamlessly into the trigger guard for invisible profile and smooth draw. Viridian's red lasers utilize a 635 to 650 nm laser wavelength to generate the brightest, sharpest red dot possible. These lasers feature 2 modes of operation (constant and strobe) and up to 12 hr battery life. The new Gen 2 models feature a new instant-on ambidextrous, inside the waistband (IWB), custom fit holster with instant-on activation. Made of microfiber, this holster is more comfortable and durable than the previous models. The instant-on activation ignites the tactical light the moment you draw. No buttons, no squeezing, no doubt. When you draw, it's on.