Or at least I think it is.
According to my local Mitsi dealer its a "control unit", but he could not say for which car.
Anyway its part number MR430872 and I want £25 inc. P&P for it as I don't know if it works or not. I was told by the guy I got it from that it did but have not tested it myself.
New price is £340 plus VAT.
See here for "WTF is it ?" thread
http://www.clubvr4.com/forum/showthread.php?t=14926