Even More proving its mastery of chronographs and especially superior-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating at a phenomenal price of 50Hz for an correct 1/one hundredth of the next chronograph operate. 1844: Adolphe Nicole introduces the reset feature, enabling https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/