Expand for usb port, supply up to 500mA current per port Adopt the second age USB controller No external power supply Drivertess.hot plug&jplay Internal over current protection circuits Support USB 1.0/1.1.compatible USB 2.0,full speed up to 12Mbps. Design with super streamline & mini Support OS:Win 95 OSR2/98SE/ME/2000/XP,Linux2.4 and Mac OS8.5 or over version Chains up to 127 USB drives