In reply to nation1:
They are very good crampons for steep ice, but you have put your finger on the major defect. Despite Si Withington's entirely correct comment that they are not intended for slogging through wet snow, one often has to do this (or descending after a route), so the omission is a gross failure. Given that they could easily have done this, at least for the rear, I suppose the motive was to shave weight, to keep the "lightest techical crampon in the world" tag for a bit longer.
Like Si says, you can bodge anti-ball plates, I have done this and it works pretty well, bodging the front with duck tape. That does not excuse the failure to provide one from Petzl though.
Post edited at 11:00