Even Further proving its mastery of chronographs and specially higher-frequency precision, ZENITH unveils the DEFY El Primero 21 using a new El Primero calibre beating at a phenomenal fee of 50Hz for an exact 1/one centesimal of the second chronograph perform. Chronographs — with their bezels, scales and sub-dials — https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/