Even Further proving its mastery of chronographs and specially high-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 correct 1/one hundredth of the 2nd chronograph operate. Chronographs — with their bezels, scales and sub-dials https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/