Further Proving its mastery of chronographs and especially superior-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 2nd chronograph purpose. Ideal for those who benefit straightforwardness around precision, the https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/