Max. is 2.4 Amps output per port. They refer to this a "fast-charging". For 4 ports at 4.8Amps output, the unit will equally divide the 4.8Amps between the number of ports that are plugged into it. So 2 devices will get 2.4Amps each. 4 devices will get 1.2Amps each. Also, 2.4Amps should not damage any device that is plugged into it. If you feel more comfortable, plug in more than two devices at a time and the unit will automatically reduce the power to each.