Further Proving its mastery of chronographs and especially large-frequency precision, ZENITH unveils the DEFY El Primero 21 with a new El Primero calibre beating in a phenomenal rate of 50Hz for an accurate one/one hundredth of a second chronograph purpose. Chopard's Mille Miglia assortment celebrates the world's most gorgeous race. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/