ah, I thought it was a typo, the S being right next to the X and all...In that case, I'm fairly sure the screw patterns are different, but I don't have any FKX bindings to look at so I can't guarantee that. The heel pieces for sure are different. the FKX heel piece mounting pattern is pretty tight, whereas the PX is longer, so you could probably get away with mounting them a 3rd time.Â