With The event of your ZENITH calibre, the Manufacture’s founder was nicely on his way to achieve his star: The creation of a trustworthy motion applying standardised output solutions. Declaring the winner with the race to create the main automated chronograph in 1969 is contentious company, so Zenith’s “El Primero” https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/