The PX-10 I bought around this time last winter came with a nearly NOS Simplex Criterium RD; the previous owner had bought it NIB from eBay after the original RD (presumably a Criterium) broke on him. His FD had also broken, and he gave it to me with the bike--in two pieces--but that had been replaced with some modern POS. (You can have that too, BC--cheap! )

Around the same time I picked up a bike with a working Prestige RD, AND got an NIB Prestige FD with Simplex paperwork. So I made a little album showing the difference between the Prestige and the Criterium, which as far as I can tell is the Prestige, beefed up with better/thicker metal around the Delrin. Stamped into the back of the Criterium plastic is 'Prestige.'

Confusingly, Simplex papers refer to both Prestige and Criterium as Model #637. I'm not sure if the /P and /NI suffixes refer to the difference in model names, or whether it has the claw attached.

http://www.bikeforums.net/album.php?albumid=314