This Usb 3.0 to Dual Hdmi Multi-Monitor Adapter acts as an external video card for your MacBook or Windows computers. It allows you to add two additional displays through your Usb 3.0 port, boosting your productivity by giving you more screen space to work from. One of the Hdmi ports can output resolutions up to 4K, while the other can output resolutions up to 2048 x 1152.