The charger needs to be plugged into a USB power supply which then allows you to charge the phone wirelessly stopping wear and tear on the delicate charging port on compatible phones (Android micro USB connectors are particularly delicate). The 4x USB output ports are included so that you can also charge multiple devices with conventional cables too. Please note the hub is not a data hub and will only facilitate charging and not data transfer.Input: 5V /1A, Output: 5V /1A. Ports: 4 x USB Ports. Charging Distance: 8mm. Charging Efficiency: 73%.