Fenix Flashlights TK16 XM-L2 U2 Rechargeable LED Tactical Flashlight, Black, 1000 lm TK16L2BK Aircraft-grade Aluminum Uses Cree XM-L2 U2 LED with a lifespan of 50,000 hours Powered by one 18650 rechargeable Li-ion battery or two 3V CR123A Lithium batteries Digitally regulated output maintains constant brightness Reverse polarity protection, to protect from improper battery installation Anti-roll, slip-resistant body design