Even Further proving its mastery of chronographs and exclusively large-frequency precision, ZENITH unveils the DEFY El Primero 21 with a new El Primero calibre beating in a phenomenal fee of 50Hz for an correct 1/a centesimal of the 2nd chronograph operate. Chronographs — with their bezels, scales and sub-dials — https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/