Additional Proving its mastery of chronographs and exclusively large-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating in a phenomenal rate of 50Hz for an accurate one/100th of a 2nd chronograph functionality. The Speedmaster gets all the enjoy in Omega’s chronograph lineup, https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/