We are no stranger to this reference here at Vision Vintage, the 2639 from the 1950's. There were many variants around at this time, from military hands to radium aged dials with applied and non applied hour markers. You can see a variety.
 
This particular example is quite rare in that it is a non luminous dial with uncommon (on this reference) feuille hands and hour markers at 3 & 9 position and that simple '12' layout. This style transforms the watch, especially with this 'French Green' honeycomb dial! It is really elegant and the perfect size at 35.5mm exluding crown.
 
There are not many of these around, and all original.
 
We paired it on a Classic Taupe with ton sur ton stitching from Jean Rousseau, Paris.