More Proving its mastery of chronographs and specially superior-frequency precision, ZENITH unveils the DEFY El Primero 21 having a new El Primero calibre beating at a phenomenal charge of 50Hz for an precise one/100th of the second chronograph function. Thank you yet again for choosing Watches World! We remain at https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/