Built-in Li-polymer rechargeable battery short-circuit,over voltage,over current protection Built-in Li-polymer rechargeable batteryshort-circuit,over voltage,over current protection4LED can display the battery balancecapacity,charging capacity and discharge capacityWith on/off switch on bottomPortable,elegant designInput:DC5.0V 500mAOutput:DC5V 1000mA 1900mA Power Bank for Iphone 4/4S