GoVision UltraTac K18 Cree 360 Lumen IPX-8 Waterproof Portable Keychain LED Flashlight with Mini AAA Battery Included (Stainless Steel) There is a AAA battery included, you can use it immediately when you get it. UltraTac K18,Brand Quality.50,000 hours lifetime/ IPX-8 Waterproof/ 1.5m Impact resistant Direct Thermal Patch (DTP) Copper MCPCB: Direct Thermal Path Copper MCPCB provide excellent heat dissipation to ensure the best light performance AR coated lens, 99% light transmittance. Light source: CREE XP-G2 S2 LED. All the joint with O-ring sealed. Support four variable lighting modes (high, medium and low) plus strobe via the side button switch 360 lumens max output. Using a 10440 li-ion battery. It also offers a 110 lumens output by using a single AAA battery You will be marveled at its negligible volume, weight. Polished finish, non-slip and comfort design. Two-way clip provide more carrying options