This is the word's first blue laser gun sight. Used for tactical and low sight situations where a distinguishable and non-beam-trace generating laser is needed. This unit has been tested by the US Army and Coast Guard for work on Picatinny mounts on the M4, M4A2 and M240. Be the first to have the new generation and color of laser sight! Rated at 50mw, it is guaranteed to perform its job well.405nm blue 40mw average output, CR123A battery powered, Picatinny mounting, Pressure switch and end cap switch provided, Only blue laser sight available