Coast ZX555 ZITHION-X Li-Ion ported rechargeable batteries are designed with an integrated micro-USB port, allowing the convenience of your battery to be charged outside your light. All Coast ZITHION-X batteries include a built-in charge level indicator showcasing the battery's charge status (solid red) when charging, (solid green) when fully charged. Simply plug a micro-USB cord into the battery port, connect the cord to an available power source, and charge. All Coast ZITHION-X batteries are protected with premium overcharge/discharge protection and are backed by Coast's one-year warranty.