1944 – 1947
Specifications
| Lignes | 12 ‴ |
|---|---|
| Mounting Diameter | 27 |
| Thickness | 3.2 |
| Frequency (vph) | 18,000 |
| Jewels | 17 |
| Hand Sizes | 1.35, 0.75 |
| Complication | Subsidiary Seconds |
| Power | Manual |
| Shape | Round |
| Size | Large |
Notes
Caliber is based on the 12.68Z meant to be a thinner version (M designation stands for 'mince', thin in French), Some Chronometer verisons known. Early versions have 15 Jewels. 17 Jewels is most common. Later examples have a redesigned pallet fork bridge.