135-O

Created by Ephrem Jobin starting in 1945, the Calibre 135 was manufactured between 1949 and 1962 in both a commercial version and a specialized iteration for observatory chronometry contests in Neuchâtel, Geneva, Kew Teddington, and Besançon. These non-commercial "O" movements were never sold or cased, but were subjected to rigorous testing across various temperatures, shocks, and six positions to ensure superior chronometric precision. With more than 230 awards, the Calibre 135-O remains the most decorated observatory chronometer movement in horological history.