1929 – 1959
Specifications
| Lignes | 12 ‴ |
|---|---|
| Mounting Diameter | 27 |
| Thickness | 4.25 |
| Frequency (vph) | 18,000 |
| Jewels | 17 |
| Hand Sizes | 1.32, 0.75, 0.22 |
| Complication | Subsidiary Seconds |
| Power | Manual |
| Shape | Round |
| Size | Large |
Notes
Earliest known example 1929 before production of more common version in 1938. You can recognize it because the old caliber had one case screw while the more common post-1938 version has two case screws. Latest versions had incabloc shock protection. Earlier shock protection system started around 1947 and were used for an arctic expedition. 12L designation started in late 1940s and was used primarily for the US market. Some chronometer versions known