Even Further proving its mastery of chronographs and especially large-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating at a phenomenal level of 50Hz for an exact one/a centesimal of a second chronograph functionality. I would happily use Watches World once again and https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/