Its a simple USB splitter. What I wanted to do is add my Logitech MX mouse and Logitech keyboard USBs to it. When I connect one of the two USBs to the port on the back of the iMac, it works fine, but nothing works when both are connected. I tried one of the two, with my HD webcam as well, and again, nothing works. I tried a different port, but again, nothing works. Is the power from the USB just not powerful enough? I have all the USB ports taken up. I have the following connected: -LG external Bluray drive -A Belkin USB/firewire HUB that has my current wired keyboard connected -Logitech c910 Webcam -USB extension cable to the front of desk, to plug in thumb drives This is what it looks like in System Report: Also, I use to have a powered usb hub connected to the iMac, where the extension is now, but ever since I upgraded to Yosemite, the hub does not work. It will read a thumb drive, but would freeze my keyboard and MX mouse. If I tried to plug in my iPad or iPhone, it would not charge, and again, the keyboard and mouse would not work. Is too much power being used, or is there something else going on?