Weltool UB18-12 18350 USB Rechargeable Li-ion Battery
***Batteries purchased without any equipment they can operate must be shipped with ground shipping. If you purchase only batteries and no flashlights/headlamps you must select UPS Ground even if other options are available unless your order meets the free shipping threshold.***
First battery I received was defective, but Killzone made it right over the weekend.
Outstanding customer support... bar none.