Even Further proving its mastery of chronographs and specially significant-frequency precision, ZENITH unveils the DEFY El Primero 21 which has a new El Primero calibre beating at a phenomenal charge of 50Hz for an accurate one/a hundredth of the next chronograph perform. 1844: Adolphe Nicole introduces the reset characteristic, letting https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/