Even Further proving its mastery of chronographs and exclusively substantial-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating in a phenomenal level of 50Hz for an accurate 1/100th of a next chronograph functionality. Chronographs — with their bezels, scales and sub-dials — https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/