The JUA250 Usb 2.0 Hdmi Display Adapter acts as an external video card for your Mac or Pc. It allows you to add an additional Hdmi monitor/display through any available Usb 2.0 port. There is no need to open up the computer to add an expensive video card. With the JUA250 you simply load the drivers, plug in the adapter to the Usb port, then plug in the Hdmi monitor cable into the adapter and you are ready.The adapter supports three viewing modes and Hdmi audio. Primary and Extended Mode allow you to have individual applications open on each monitor, vastly improving productivity and extending your desktop across multiple displays, which is great for spreadsheets. Mirroring Mode is used to clone one screen onto another, which is ideal for presentations. In addition, you can plug-and-play between your computer and a second monitor or projector, to create new visual environments in seconds