Even More proving its mastery of chronographs and exclusively higher-frequency precision, ZENITH unveils the DEFY El Primero 21 by using a new El Primero calibre beating at a phenomenal level of 50Hz for an precise 1/a centesimal of the second chronograph purpose. Equipment Patrol editors chose the Blancpain Air Command https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/