Swiss made, manually wound, based on a design development project titled “27 CHRO C12” (27 mm diameter, chronograph, with extra 12-hour register) took place in the 1940’s by Albert Piguet and Jaques Reymond as a joint developement project between Omega and Lemania. Launched in 1942, the 27 CHRO C12 later became known as the Lemania 2310, or Omega c.321.