SureFire X300 Ultra Series LED WeaponLights with TIR Lens Special off-white high-performance LED produces 600 lumens biased in the yellowish-green spectrum optimal for human vision Precision TIR lens creates a smooth, tight beam with enough surround light for peripheral illumination Integral, ergonomic one-finger ambidextrous momentary and constant on switching Instantly attaches to both Universal and Picatinny accessory rails.FITS: The new T-slot mounting system fits most railed handguns (and rail-equipped long guns) but adapter mounts are available for some non-railed handguns Accepts optional pressure-activated switches for precision control without altering grip on weapon