Audio/video signal switcher.
Not sure why I bought this, but I must have had a reason.
It's used to switch an audio/video signal between four different devices from a single source. For instance, if you have a plain jane vcr that you might want to switch between found different TVs, you could use this switcher to do that rather than wrestling with cables.....
You could also use it for some sort of security monitors as well...
Asking $25.