Even Further proving its mastery of chronographs and specially high-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating at a phenomenal price of 50Hz for an correct one/100th of a second chronograph perform. I purchased a watch from Watches World and the https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/