Even Further proving its mastery of chronographs and especially higher-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating in a phenomenal rate of 50Hz for an precise one/one hundredth of a second chronograph function. Tudor’s Black Bay line is on fire with collectors. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/