The JUD380 USB 3.0 Mini Dock acts as an external dual monitor display for your MAC or PC. It allows you to add an additional monitor/display through your USB 3.0 port. No need to open up the computer to add an expensive video card, with the USB 3.0 Mini Dock you simply load the drivers, plug the adapter into the USB port, then plug in the VGA or HDMI monitor cable into the adapter and you are ready. It supports three viewing modes. Primary mode, allows you to have individual applications open on each monitor, vastly improving productivity. Extended mode allows you to extend your desktop across multiple displays, great for spreadsheets.