Zenith developed the El Primero, one of the first automatic chronograph movements, in 1969.
The movement was introduced during a landmark year for mechanical chronographs, alongside competing automatic designs from other Swiss manufacturers. Its name means “the first” in Spanish, reflecting Zenith’s positioning of the calibre as a pioneering achievement.
The El Primero became especially notable for its high-beat frequency of 36,000 vibrations per hour, allowing the chronograph to measure tenths of a second. That frequency also helped distinguish it from many slower mechanical movements.
A common mix-up is treating El Primero as the name of a watch brand. It is a movement family created by Zenith; the brand itself is Zenith, founded in Le Locle in 1865. The movement has continued in modern Zenith chronographs and has also been used in selected watches from other companies.