The USB 2.0 VGA Display Adapter acts as an external graphics card for your Mac or PC. It allows you to add an additional VGA display through your USB 2.0 port. There~s no need to open your computer to add an expensive graphics card. With this adapter, you simply load the drivers, plug the adapter into the USB port, plug the VGA monitor cable into the adapter and you are ready to go. The Display Adapter 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, which can be great for spreadsheets. Mirroring Mode is used to clone one screen onto another, which can be ideal for presentations.