These compact polymer flashlights use LEDs that work in conjunction with a high-efficiency deep parabolic reflector to create a usable beam. The tail-cap switch provides momentary or constant-on functionality. The waterproof design in combination with its impact and chemical resistant glass-filled nylon polymer housing, make these some of the toughest tactical lights around. Power comes from a pair of included CR123 Lithium batteries. (Not compatible with rechargeable batteries.)