(1)Do not used for charging?, it is used for offering more usb ports to Transfer file (2)Thespecification of the power supply?is 3.5*1.35mm5V 1A,??it support? less than 1TB hard disk , if your hard disk is? more than 1TB , then the power supply not suit you (3)There are 9 options in this link , if you want usb 3.0 with power apply , please choose the right option you need (4) The power supply can solve the problem of insufficient power supply, if you need work with a hard disk , then you should choose the with power supply , and please note ,please dont use more than 2 hard disk at the same time (5) The power supply? can improve the usb transmission speed, insufficient power supply will lead to reduced data transmission, error code, with power can improve reliability. 1. 100% brand new and high quality 2. Hot plug & play USB device 3. Fully compatible with USB specification version 3.0/2.0 4. With blue LED for power 5. ON/OFF switches activate or deactivate individual ports 6. Designed with 4-port,7-port,this compact USB 3.0/2.0 high-speed hub is small enough for travel,and cable enough 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:Upto 5Gbps Color:Black/White Compatible: WindowsXP/Vista/7 and MAC OS 9.1 or higher