Even Further proving its mastery of chronographs and especially significant-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating at a phenomenal charge of 50Hz for an exact 1/a hundredth of a second chronograph purpose. This was the result of intensive R&D with https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/