This is a Surefire Flashlight known as the M340, model M340C-TN-PRO.
SureFire makes some of the finest Suppressors" Flashlights" Weaponlights; Lasers" Ear Protection; Firearm Components" and Tactical equipment on the market today.
Features:
500 Lumens
1913 Picatinny Mount
M-LOK Mount
On/Off Tail cap