This is an extremely rare Prototype dedicated cabinet. It's the same style cabinet as Crystal Castles. It has beautiful silk screened side art and kick panel art. This is the same machine talked about on Most all C&D's were kits to convert Defender cabinets.
I know of only two other machines like this one, but what makes this one really interesting is the "Atari Key Club" plate on the front of the control panel. The artwork is hand-drawn with a marker. There's a hole in the plate and on the inside there's some sort of mechanism with wires. I suspect there was a lock in the hole and a person would try a key in it and if it worked, something special would happen, like a free credit or something. The wires on the mechanism don't go anywhere, so who knows how it really worked.
The picture used in the KLOV is of this very machine.