In the 1940's, Lemania and Omega worked together on a project called “27 CHRO C12” to develop a 27 mm diameter chronograph with a 12-hour register. Lead by Albert Piguet and Jaques Reymond, this project resulted in the 1942 launch of the Lemania 2310, called Calibre 321 by Omega.
This movement was famously used in the Omega Speedmaster from 1957 through 1965 as well as the Omega Speedmaster Professional from 1965 through 1968, where it gained fame as the “moon watch” movement. It was also used in the Omega DeVille, Omega Seamaster, and watches from Patek Philippe (as Cal. 2872).
The Lemania 2320 was closely related but included a swan neck regulator, 4 extra jewels (21 total), and other refinements.
In 2019 it was announced that Omega had been working in secret to re-create the classic Cal. 321 with modern technologies. The so-called “Alaska 11” project would create a new Omega Speedmaster watch for the 50th anniversary of the Apollo 11 moon landing.
Calibres 2310 and 2320 are used as the ebauche and base design for the many prized chronograph movements from names like Patek Philippe, Vacheron Constantin, Breguet, and Roger Dubuis. It is widely regarded as one of the finest such movement designs in history.