Wristwatch: wanted large Zenith chronometer with the legendary calibre '135', ca. 1948: Ca. Ø35mm, 18K gold, pressed back, case number 488200, back with weakly legible owner's engraving, inside punched with Zenith, manual winding calibre 135, chronometer calibre, fine adjusting device, movement number 3869895, striping decoration, silvered dial, pink gold indexes, pink gold hands, like new leather strap wit buckle, in well-kept condition, rarity. Ephrem Jobin introduced the legendary Zenith calibre 135 in 1948. This was a time when many watch manufacturers competed for the highest scores in precision during observatory testing. Calibre 135 featured several technical innovations that enabled it to win a number of awards and prices in the tests. Amongst those was a series of five consecutive prizes at the tests in Neuchâtel from 1950 to 1954. The movement type won a total of 200 awards, of which two thirds were first prizes. Ephrem Jobin developed a larger barrel for the new calibre 135 to improve the isochronism and the power reserve. He also used an extra large balance to achieve higher precision during regulation (higher rotational inertia gives a more consistent performance without increasing the weight or the number of beats). This approach initiated a complete rethink of movement design: amongst other things the minute wheel was removed from the centre of the movement to create additional space for a larger balance. The model entered for observatory testing was fitted with a Breguet overcoil and an eccentric fine adjustment mechanism intended to guarantee a well-balanced friction and a perfect fine adjustment.