Even More proving its mastery of chronographs and particularly higher-frequency precision, ZENITH unveils the DEFY El Primero 21 using a new El Primero calibre beating in a phenomenal charge of 50Hz for an correct 1/a hundredth of the 2nd chronograph function. 1844: Adolphe Nicole introduces the reset characteristic, enabling unique https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/