Likely conceived by Martel and shared with Zenith, Calibre 285 was introduced around 1942 and produced for half a century after. Calibre 285 and its relatives remained competitive all that time thanks to solid engineering, including an 8-column pillar wheel design, two button operation, and compax design.
Calibre 285 used Martel's variable-diameter plate technology By interchanging cam plates, the movement could be produced as 14, 15, 15.25, or 15.75 ligne sizes (Calibres 285, 287, 288, and 292, respectively). The later Calibre 385 and Calibre 387 were variations on Cal. 285 and 287 with flat hairsprings instead of Breguet hairsprings.