Founded in 1865 by Georges Favre-Jacot, Zenith has a rich history in the manufacture of Swiss timepieces by producing watches which have become icons. The most notable achievement was the creation of the first integrated automatic chronograph movement - the Zenith El primero - which still to this day is the most precise series-made calibre. The opening in the dial of Zenith's El Primero Chronomaster Open Power Reserve allows its wearer to glimpse the beating heart of the legendary chronograph movement, beating at 36,000 vibrations per hour.