Any HDMI splitter will let you use two monitors, but it will only mirror the image on both displays. To “extend” your display, or expand your desktop to span two monitors, you will need to use an adapter or USB-C hub that converts video out from a compatible port, such as a Thunderbolt or DP Alt Mode-enabled USB-C port, or Mini DisplayPort, to a dual-HDMI connection. Depending on your computer, you may also simply be able to connect two monitors using two separate ports. Most desktops, particularly gaming PCs, support multiple DisplayPort and HDMI connections. Some laptops may feature a single HDMI and a video-capable USB-C port.