Cal. 39 is a column wheel chronograph movement produced by Landeron (Charles Hahn & Cie.) in the 1940s. It features a Breguet hairspring, screwed balance, and regulator index. It used a horizontal clutch and column wheel but was plainly finished and utilitarian.
Cal. 42 was similar but used a flat spiral hairspring and added an hour counter register. A new chronograph mechanism was fitted for the derived Cal. 52. Cal. 53 was a more radical departure, with a cam-switching chronograph mechanism from Dèpraz similar to the Landeron/Dèpraz Cal. 48.
Cal. 39 was commonly used by Nicolet watch and Breitling.