Wacom makes a non-standard HDMI cable, and the converter makes a standard HDMI cable electrically look like a Wacom HDMI cable.

For the Cintiq Pro 24 you must use the “XOOT Converter” HDMI adapter, or the screen will not show the HDMI input!

The adaptor is included with all Wacom Kits as a “just in case” that a firmware upgrade starts to check for a Wacom HDMI cable and no longer accepts standard HDMI cable.