I actually bought one of those monsters, because it was cheap--I like cheap!

Yes, basically, it is a ps2 cable with a terminal block on the end. The encoder chip is burried under the terminal block in a chunk of epoxy. And yes it idoes just have 12 inputs (wasn't aware of that when I bought it).

I'm using it in conjunction with a pad hack in a 2 player CP.
It works...but bang for the dollar...look elsewhere! You've been warned!