Zenith El Primero

Introduced by Zenith in 1969, the El Primero is widely celebrated as one of the world's first automatic chronograph movements. Its high beat rate of 36,000 vibrations per hour (vph) allowed for precision timing down to 1/10th of a second, an industry breakthrough.

Yes, in the late 1980s, Rolex modified the Zenith El Primero calibre 400 to power their iconic Daytona chronographs. Rolex stripped the date function and lowered the beat rate, utilizing the movement in the Daytona reference 16520 until 2000.

The name translates to The First in Spanish, reflecting Zenith's claim to being the first to market with a fully integrated, automatic chronograph movement. While Heuer, Breitling, and Seiko were also racing to release automatic chronographs in 1969, Zenith unveiled theirs in January of that year.

When Zenith decided to halt mechanical watch production in the 1970s, management ordered the El Primero tooling to be destroyed. A former employee named Charles Vermot secretly hid the machinery and blueprints in the attic, saving the movement from extinction.