Even More proving its mastery of chronographs and precisely higher-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating at a phenomenal level of 50Hz for an exact one/one centesimal of the next chronograph perform. Tudor’s Black Bay line is on fireplace with collectors. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/