Longines calibre 13ZN After an approximately 23-year production of the 13.33Z chronograph, in 1936 Longines began to produce one of the most technologically advanced chronograph movements at the time – the calibre 13ZN. As we mentioned at the beginning, Longines developed the first chronograph for the wristwatch – the 13.33Z – but this was the first chronograph mechanism equipped with the flyback, or retour-en-vol, function. The 13ZN had 17 jewels; a diameter of 29.80 mm and height of 6.05 mm, and beat at 18,000 vph, and was equipped with a Breguet hairspring. Rare collector's watch from Longines Original dial. Original movement. Great condition. Manufacturing year of the watch circa 1940 Movement diameter: 29.8mm Size of timepiece: 37.4mm without crown. Original dial silver-coloured Two auxiliary dials. Rare small second at the nine. Chronometer by the three. Movement calibre 13ZN in original condition - movement functions - a calibre which makes collectors' hearts beat faster and is one of the most popular calibres ever A manufacture movement of masterful quality. The pressed back lid is marked ACIER INOX Longines Logo 7057761 under the 12 The timepiece is in original condition and was not refurbished (refinished) and exhibits minor signs of wear. Leather strap Longines 18mm - length 23.5cm Interesting, sought-after, collector's watch in very good condition. Insured shipping with Austrian postal service.