Further More proving its mastery of chronographs and precisely significant-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating at a phenomenal amount of 50Hz for an correct 1/a centesimal of a 2nd chronograph purpose. All our initiatives were directed in the direction https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/