Further More proving its mastery of chronographs and precisely significant-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating in a phenomenal rate of 50Hz for an exact one/one hundredth of a next chronograph operate. Now decades because its debut, TAG has once again https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/