Further More proving its mastery of chronographs and exclusively superior-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating at a phenomenal price of 50Hz for an correct one/a hundredth of the next chronograph function. Tudor’s Black Bay line is on fire with collectors. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/