Hello,
I hope everyone is in good health.

I am thinking of picking up an Arca Swiss 13x18 camera. The one I am looking at seems to be a 'C' model. Does anyone know which ground glass holder options there were? In the system overview sheet I found there are three of them pictured (8.10, 8.11, and 8.12), at least two of them seem to differ. Are those just different ground glass markings or does one of them take the old 13x18 single-sided metal holders?
Is the difference (if any) visible?

Thanks for the help and best wishes,
David