Even Further proving its mastery of chronographs and exclusively high-frequency precision, ZENITH unveils the DEFY El Primero 21 by using a new El Primero calibre beating in a phenomenal rate of 50Hz for an precise 1/one hundredth of a next chronograph operate. Chronographs — with their bezels, scales and sub-dials https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/