3 NO COLLECTION , ONLY SENT BY POST , FREE DELIVER WITH IN 1 TO 3 DAYS DO not use it for charging ,it is used for offering more usb ports to transfer files. 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 Features: 100% brand new and high quality Hot plug & play USB device Fully compatible with USB specification version 3.0 With blue LED for power ON/OFF switches activate or deactivate individual ports Designed with 4-port,7-port,this compact USB3.0 high-speed hub is small enough for travel,and cable enough to meet your connectivity needs The specification of the power supply is 3.5*1.35mm, 5V 2A. Specification: Item Name:USB HUB 3.0 / 2.0 USB Ports:4 , 7 Cable:USB 3.0 About 605mm, USB 2.0 About 400mm Size:104*35*21mm, 164*35*21mm Data Transfer Rate:Upto 5Gbps/480mbps Color:Black Compatible: WindowsXP/Vista/7 and MAC OS 9.1 or higher