Even Further proving its mastery of chronographs and particularly large-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating at a phenomenal amount of 50Hz for an exact one/100th of the next chronograph purpose. All our efforts were directed in the direction of https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/