The Acebeam IMR 21700 battery is a rechargeable battery and power bank wrapped into one incredible cell. The high capacity 5100mAh drain allows this battery to charge while also recharging other devices through an Input/Output USB cable. Make it easier to charge up your battery and other devices with this 21700 on hand. The Acebeam IMR 21700 features an LED indicator that glows red during charge and green when fully charged for a clear signal that your battery is ready for optimal use. Throw this battery into the compatible Acebeam flashlight (sold separately) for excellent output and access to all features.