Further Proving its mastery of chronographs and specially large-frequency precision, ZENITH unveils the DEFY El Primero 21 with a new El Primero calibre beating at a phenomenal level of 50Hz for an exact one/100th of the 2nd chronograph purpose. All our attempts ended up directed in the direction of providing https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/