3R stuff goes nuts on eBay, I've watched.

The pic looks like some sort of special collet holder. The blue line is a
flush line to connect to the sinker EDM supply. The AL plate will bolt on
the head. I see a contact to connect the auxilliary elctric supply. I'd
guess the top on the holder itself has a bolt to tighten a collet.

There's a couple piecs for a wire EDM in the lot I'D LOVE TO HAVE.

Karl