Even More proving its mastery of chronographs and particularly substantial-frequency precision, ZENITH unveils the DEFY El Primero 21 with a new El Primero calibre beating in a phenomenal rate of 50Hz for an accurate one/one centesimal of the second chronograph purpose. The Speedmaster will get many of the like in https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/