The Nitecore NL2150R is a next-generation 21700 battery that can be found in many of their newest lights. The 21700 battery is taking the lithium power solution and flashlight industry by storm, and Nitecore is here to help. This battery has 3.6 volts and a high 5000mAh capacity for superior runtimes. The built-in USB-C port is for convenient charging when you can't get to or do not have an external charger. Capable of being recharged hundreds of times saves you time and money by not buying new cells. The stable 5-year shelf life makes it possible to safely store these when you need them the most.