This power bank is mainly designed for charging portable digital devices. It's a Li-Polymer power bank with Female Micro USB for its battery charging, Female standard USB and a bulit-in Micro USB cable (with 1 Lightning connector) for discharging. The voltage and current of discharging are constant. There is a Micro Control Unit(MCU) in the power bank, intelligently controlling charge and discharge. Built-in vibrating switch, shake the power bank appropriately to start it. The built-in battery is equipped with double protections (hardware and software). 4-LED power indicators, indicate the actual power.