Autonegotiates for speed and duplex. A DIP switch enables Link Fault Pass-Through to be turned on and off for better troubleshooting. Powered by the included universal AC power supply, a PC's USB port (with optional USB Power Adapter Cable), or the optional rackmountable PowerTray. Auto MDI/MDI-X means you never need to worry about what kind of cable to use. MultiPower Miniature Transceiver/Media Converter 100-240-VAC, 50-60-Hz Adapter