The ARB-L18-2600U is a high capacity 18650 Li-ion rechargeable battery with a built-in micro-USB charging port. It also includes a protection circuit in the anode to help prevent short circuits, over charge/discharge and over heating. This battery can quickly be charged without the need for a separate charger. This not only save you money from purchasing a charger, but also convenience of not having to carry around another device. FeaturesMicro-USB charging port2600mAh high capacityProtection circuitry to prevent short circuitsPressure vents to prevent explosions500 charge cycles