This is NOT a powered USB hub. The fact that is has "power switches" that turn on blue LED lights is a bit misleading in that regard. If you have a device that must receive power to access its USB functionality (ie, iPhone), this is NOT a good device to purchase. (iPhone won't register as being plugged in if you use this device). If you have multiple peripherals battling for easy-access USB port space on your computer, then this is a nice device to fill that need. As for the power issue... There are no specifications as to what type of power adapter you need if you DO want to power the device. I contacted customer support and their response to this question was: "Thank you for your email. It should be the 5V." So... that's part of the answer, but no info as to proper amperage. The port for the adapter is a coaxial type power plug.. I would estimate 4mm, but will probably end up needing to make a trip to a radio shack, device in hand, to find a matching 5V adapter plug if the lack of power becomes an issue. (or keep shopping Groupon for a *powered* USB hub). .