Further More proving its mastery of chronographs and specifically large-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating at a phenomenal price of 50Hz for an accurate 1/100th of a 2nd chronograph operate. Tudor’s Black Bay line is on fireplace with collectors. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/