Product OverviewThis is the NEW AND IMPROVED TK15!The new TK15S2 features a powerful, tough, durable, and fully waterproof design intended for harsh outdoor conditions. It operates on one 18650 Li-ion battery or two CR123A Lithium batteries. The multi-level dimmer function makes a perfect combination of extreme brightness and ultra-long runtime. The innovative side dimmer operation is very simpole and rapid. This light is perfect for hunting, searching and rescuing, etc.