Further Proving its mastery of chronographs and exclusively superior-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating in a phenomenal fee of 50Hz for an accurate 1/one centesimal of the next chronograph purpose. To promote the art of watchmaking to as Many https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/