I noticed that some of the cases had a different setup of the holes in the ear-piece. The 3 Dutch PTT Ericofons (Red, Brown and White) always have the ‘small’ setup. I have not seen another version there.
But sofar these PTT phones are the only ones I have seen with the small version, except for the Persian Gray which I have in both versions as you can see. On the left the small version, on the right the large. It is just a small detail that I ran into. Not that important.