More Proving its mastery of chronographs and especially substantial-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating at a phenomenal amount of 50Hz for an accurate 1/100th of a 2nd chronograph functionality. Chronographs — with their bezels, scales and sub-dials — tend https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/