More Proving its mastery of chronographs and particularly higher-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating in a phenomenal level of 50Hz for an precise one/a centesimal of a second chronograph perform. Chronographs — with their bezels, scales and sub-dials — https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/