This 21700 battery from Fenix is designed to handle the additional power and capacity for high lumen flashlights giving them longer run times. What makes this 21700 battery even better is the USB Type-C charging port that is embedded in the cell. You don't have to use a separate charger to charge the battery; it can all be done with a wall adapter and USB Type-C charging cord. It is likely that you already have these in your home since many cellphones use this same type of charging port.

Shipping Note: Lithium ion batteries cannot be shipped via expedited shipping service due to shipping carrier restrictions. Orders that include lithium ion batteries that aren't included in lights they are meant to power will be shipped via UPS or USPS ground service.