The Elite Force Axeon MPL1 Pistol Flashlight.  Fits and mounts on all standard lower railed pistols and other guns.  High quality made for real guns, but great for airsoft use too. 120 lumens of bright white light with on/off, strobe, and slow flashing options toggle. Easy to install with a simple allen tool.  30 minutes of run time on one (1) AAA battery.

Very compact, bright, and reliable light.  Recommended for pistol setups.