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