More Proving its mastery of chronographs and especially high-frequency precision, ZENITH unveils the DEFY El Primero 21 by using a new El Primero calibre beating at a phenomenal fee of 50Hz for an precise 1/one centesimal of the second chronograph operate. Tudor’s Black Bay line is on fire with collectors. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/