I consider myself a hardcore fan, but I am a bit dumb on this topic.

skywalker said:

I may be wrong, but I believe it was a portable keyboard that he and sometimes Tommy Barbarella would play at the front of the stage. It was a custom shape, with a neck a bit like a guitar.... Can't remember when I last saw it in action, but possibly on the Rave DVD...

It's a magical synthesizer that only works when the musician is swinging on wires and wearing velvet platform heels.