Further More proving its mastery of chronographs and specifically significant-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 1/one hundredth of the second chronograph function. Tudor’s Black Bay line is on fireplace with collectors. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/