COAST ZX110 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. BATTERY CHARGING LEVEL INDICATOR: Check the status of your batteries charge level with our built-in charge level indicator. (Solid red) when charging, (solid green) when fully charged. OVERCHARGE/DISCHARGE PROTECTION CIRCUITS: Over charging and improperly discharging lithium batteries can cause a safety concern and hazerdous risk to the user and it's surroundings. COAST batteries are built with overcharge/discharge protection, ensuring you and your battery are protected.