Even More proving its mastery of chronographs and specifically large-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating at a phenomenal fee of 50Hz for an accurate 1/a hundredth of the 2nd chronograph operate. This was the results of intense R&D via https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/