This is Double Battery pack Discharge Converter, it is used for E-bike which has 2 batteries.Suitable 500W Hub Motor. This device is used for managing 2 batteries supply power to E-bike or dual-charge two battery at same time.It has 2 inputs and 1 output both are XT60 connector. Warning: This device will ONLY work with geared hub motor and middle motor,we don't suggest use with gearless motor.The usage with gearless motor which may lead damage or burn of battery or controller and we are not responsible for that.