Additional Proving its mastery of chronographs and exclusively substantial-frequency precision, ZENITH unveils the DEFY El Primero 21 that has a new El Primero calibre beating at a phenomenal level of 50Hz for an precise 1/one centesimal of the second chronograph function. Inspired by British pilot’s watches in the seventies, Hamilton’s https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/