Fenix 21700 Rechargeable Li-Ion Battery – 5000 mAh

This 21700 battery from Fenix can handle twice the power of a standard 18650 battery. The additional mAh's allow flashlights like the PD36R and TK22 to have 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.

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