Even More proving its mastery of chronographs and particularly large-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating in a phenomenal charge of 50Hz for an exact one/one hundredth of the 2nd chronograph function. Chronographs — with their bezels, scales and sub-dials — https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/