More Proving its mastery of chronographs and especially significant-frequency precision, ZENITH unveils the DEFY El Primero 21 using a new El Primero calibre beating at a phenomenal rate of 50Hz for an accurate 1/a hundredth of a 2nd chronograph purpose. Chopard's Mille Miglia assortment celebrates the world's most beautiful race. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/