quattro[Moderator]
7425
"RA" means "Remontoir Ancre" or stem-wound with lever escapement.
So it's a description of the type of caliber.
And 13''' means 13 "lignes", which is a unit of measurement for watch movements (not a reference number).
1 Ligne=2.25583 mm (1 mm=0.4433 lignes).
So 13''' (13 lignes) means that the movement is 29,33 mm in diameter.
Best, Emmanuel