Agreed, they do seem to be more custom-oriented. My 95xp800 came with one, but I've never actually tried it as I had a whole pump to go on it after I got it running. The other is still in a box, but here's teh weird part. If you screw it onto the pump, it's longer than the pump housing. At first I thought, DUH, because of the pump extension. But now I'm wondering about the dirveshaft length... That same driveshaft used to spin the regular impeller... How does that work when the impeller sticks out further?