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 level of 50Hz for an precise 1/one hundredth of a second chronograph perform. Now decades because its debut, TAG has once again https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/