Zenith is one of the most historically significant watch brands in the world, founded in Le Locle in 1865 by Georges Favre-Jacot at the age of 22, and operating continuously from the same premises ever since. The brand's greatest achievement came in 1969 when its team, led by Charles Vermot, developed the El Primero — one of the world's first automatic chronograph movements, operating at a high frequency of 36,000 vibrations per hour that allowed the movement to measure elapsed time to one-tenth of a second, a precision unprecedented in a production watch chronograph. When Zenith was ordered to discontinue mechanical development in favor of electronics, Vermot hid the El Primero tooling in the attic of the Le Locle manufacture — an act of quiet rebellion that preserved it for eventual revival and commercial licensing to Rolex for the Daytona. The El Primero's legacy is central to Zenith's identity. The Chronomaster, El Primero Original, Defy, and Pilot collections span vintage chronograph nostalgia to high-frequency modern watchmaking. Pre-owned Zenith watches, particularly El Primero-equipped references, are among the most undervalued serious mechanical watches in the secondary market. DeMesy & Co. in Dallas has been a source for pre-owned Zenith watches since 1987.