USB 3.0 HUB Multi USB Splitter 7 Port suitable for many occasions: Widely used in computers, laptops and other devices that require usb ports for external display or expansion. Great for use at home or in a dorm room. PLEASE NOTE Do not used for charging , it is used for offering more usb ports to Transfer file 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 There are 9 options in this link , if you want usb 3.0 with power apply , please choose the right option you need 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 don't use more than 2 hard disk at the same time 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. Features 100% brand new and high quality Hot plug & play USB device Fully compatible with USB specification version 3.0/2.0 With blue LED for power ON/OFF switches activate or deactivate individual ports 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 Specifications Item Name:USB HUB 3.0/2.0 USB Ports: 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 Compatible: WindowsXP/Vista/7 and MAC OS 9.1 or higher