(1) Not used for charging, used to offer more usb ports to transfer files
(2) The power supply specification is 3.5 * 1.35mm 5V 1A, it supports less than 1TB hard disk, if your hard disk is more than 1TB, then the power supply does not suit you
(3) There are 9 options in this link, if you want powered usb 3.0, please choose the right option you need
(4) The power supply can solve the problem of insufficient, if you need to work with a hard disk, then you should choose the power supply, and note that you do not use more than 2 hard disks at the same time.
1. 100% brand new and high quality.
2. Hot Plug & Play USB Device
3. Fully compliant with USB specification version 3.0 / 2.0
4. With blue power LED
5. ON / OFF switches enable or disable individual ports
6. Designed with 4 ports, 7 ports, this compact high-speed USB 3.0 / 2.0 hub is small enough for travel and has enough cable to meet your connectivity needs.
Item name: USB HUB 3.0 / 2.0
USB ports: 4, 7
Cable: USB 3.0 HUB is about 605mm, USB 2.0 HUB is about 400mm
Size: 104 * 35 * 21mm, 164 * 35 * 21mm
Date transfer rate: up to 5 Gbps
Color: black / white
Compatible: WindowsXP / Vista / 7 and MAC OS 9.1 or higher