The Fenix T (Tactical) series features a powerful, solid, durable, and waterproof design intended for rugged outdoor and military use. It’s as solid as a tank. The TK11 uses 2 CR123A or 1 Li-Ion Rechargable 18650 batteries and maintains excellent constant brightness with two output modes: General mode, which can last for a whole night and can be used for general illumination, and Turbo mode, which can be used whenever high-powered light is needed – search and rescue, long-range target identification, etc.