Yes, I confirm!
It's a 17''' SAV (savonette) PS (petite seconde) caliber Has already been said the pocket watches which houses this caliber.. If you want to find the same antique and traditional design in a PP wrist movement, you have to look the 12-120 caliber... I thin...
There is a modern reincarnation of this beauty...
albeit with improved performance (e.g. 7 day power reserve) and from an unexpected source (image: Franck Muller): Best, Magnus ...