More Proving its mastery of chronographs and especially superior-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating in a phenomenal price of 50Hz for an correct one/100th of a 2nd chronograph function. ZENITH continues exploring creative watchmaking remedies whilst developing the El https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/