Murideo AC-FXHD-KIT Fox and Hound HDMI Test Kit/18Gbps/4K/HDR/4x4x4 (Video and Audio HDMI Distribution Testing KIT built with the custom and commercial integrator in mind)

An invaluable tool for troubleshooting HDMI issues, and a bargain at this price. Any integrator who doesn't have one of these in their toolkit is making a big mistake. It will pay for itself the first time you avoid installing gear and cables that do not work well together.