Even More proving its mastery of chronographs and specifically significant-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating at a phenomenal level of 50Hz for an exact one/100th of the next chronograph perform. Impressed by British pilot’s watches in the 1970s, Hamilton’s Khaki https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/