The year was 1969, and one of the last great problems in watchmaking lay unsolved: how to make an automatic chronograph. Zenith changed watchmaking forever when they introduced the watch aptly known as “El Primero” (the first), the first self-winding chronograph watch with a full-sized rotor. El Primero was also the first automatic chronograph with a balance to tick at 36,000 vibrations per hour, which at the time was the fastest any watch could claim. Fast-beat watches offer better accuracy because they divide time into smaller fractions of a second.

Two other automatic chronographs also debuted that year, but El Primero is the only one still available today – a testimony to its reliability and beauty. The El Primero Open Power Reserve Chronomaster combines the classic shape of the original El Primero with an elegant window in the dial that lets you both hear and see one of the fastest beating hearts in watchmaking. The finishing flourish is the power reserve which shows the number of hours (up to fifty) of energy stored in the automatically wound mainspring.  A watch that made history, dressed to the nines –your heart will beat faster too.