Further More proving its mastery of chronographs and precisely higher-frequency precision, ZENITH unveils the DEFY El Primero 21 by using a new El Primero calibre beating in a phenomenal price of 50Hz for an correct one/100th of a next chronograph purpose. Impressed by British pilot’s watches with the 1970s, Hamilton’s https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/