Further More proving its mastery of chronographs and exclusively significant-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 accurate one/one centesimal of the next chronograph purpose. Complication: Refers to any check out movement beyond https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/