999 4 piston / 4 pad calipers on an st4s, these are must better than the standard calipers, just watch if you service them as there are a little sharp so go easy if your using the front brake in a corner for the first 100 miles or so. Also i switched to a set of second hand front discs that had done a few track days and were not warped. These are my 4th set of discs and they are still ok.