Additional Proving its mastery of chronographs and specifically superior-frequency precision, ZENITH unveils the DEFY El Primero 21 using a new El Primero calibre beating at a phenomenal amount of 50Hz for an precise 1/a centesimal of the next chronograph function. Be event ideal: Try to remember The fundamental rules: black https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/