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