The ref. 666, the ref. 866 (special version: believed to have been a "military dial" prototype), the ref. 1832 "Jumbo" and the ref. 3508 (special version: 500'000 A/m). Cheers, HSTE ...
To make the movement a-magnetic, they used rubies as rotor ball bearings (like in the compass watch). And for the balance spring they used a new alloy which could not be magnetized. However, the alloy was an issue in terms of accuracy and production and i...