Even More proving its mastery of chronographs and particularly large-frequency precision, ZENITH unveils the DEFY El Primero 21 by using a new El Primero calibre beating in a phenomenal charge of 50Hz for an accurate one/one centesimal of a next chronograph purpose. 1844: Adolphe Nicole introduces the reset attribute, allowing https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/