Additional Proving its mastery of chronographs and specifically higher-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating at a phenomenal amount of 50Hz for an accurate 1/a centesimal of the next chronograph operate. Tudor’s Black Bay line is on fire with collectors. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/