Even More proving its mastery of chronographs and particularly significant-frequency precision, ZENITH unveils the DEFY El Primero 21 with a new El Primero calibre beating at a phenomenal rate of 50Hz for an correct 1/a hundredth of a second chronograph functionality. This was the result of intense R&D from the https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/