The JUA354 USB 3.0 to 4K HDMI Display Adapter serves as an external graphics card for your Mac or PC. You can add an additional monitor or display through your USB 3.0 port without having to open your computer to install an expensive graphics card. With the USB 3.0 to Dual HDMI Multi-Monitor Adapter, you simply download the drivers, connect the adapter to the USB port, plug the HDMI monitor cable into the adapter, and you're ready to go. The adapter supports three display modes. In primary mode, you can open individual applications on each monitor, significantly boosting productivity. In extended mode, you can stretch your desktop across multiple displays, which is excellent for spreadsheets.