Hi,
yes Carlo, I agree, these 1st ex 2446C are fantastic,
although this one has the red second hand from 2nd ex, fluted pushers from 3rd ex and a later crown.
Dial is the later one of the two 1st ex dials I have seen, also with smaler subdials than ex 2. Perhaps serial > 112/3xxx
Some of the 2446C have an engraving on the back, some come without. I still have no idea about the rule.

If one do not see a 1st and 4th ex 2446C side by side , one may not understand it.
A 4th ex is a colorful great looking watch, a 1st ex has more charisma may be because of the more brownish, instead green lume markers, and the muted/faded red of the bezel.... ?

cheers mich