... transfer rate 1.5/12/480Mbps3) Supports up to 127 USB devices4) Extensively compatible with scanner, digital camera, digital vidicon, ... Optical mouse, keyboard, U disk etc.5) Single chip integrated USB HUB controller with embedded proprietary processor6) 4 ports, and power ... up to 500mA each port7) USB bus power Supply ,No external power supply required8) Truly plug ...