More Proving its mastery of chronographs and specially large-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating in a phenomenal rate of 50Hz for an precise 1/one hundredth of a second chronograph perform. I purchased a watch from Watches World and the https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/