Though Zipp could have called that wheel the 'sub9 clincher' disc, at the time it came out there was only the 900 (tubular) disc, so that wheel is the 900 clincher disc.
It is not as wide as the sub9 disc. I measured mine at 26.6mm at its widest point. The sub9 tubular is 28.5mm wide. That difference was enough for the 900 clincher to work for on one of my bikes when the sub9 didn't quite fit.