References in the Grail Atlas catalog made in Le Locle.
Le Locle sits in the valley below La Chaux-de-Fonds and shares the same trade tradition, gridded streets, watchmaker apartments above ground-floor ateliers, a horology school dating to the 1860s. Tissot, Zenith, Mido, and Doxa all keep their manufactures here; the Tudor manufacture in Le Locle is where the MT calibres are made. Le Locle was the home of the El Primero in 1969, the only high-frequency automatic chronograph caliber to survive the quartz crisis in continuous production. Le Locle and La Chaux-de-Fonds together are a UNESCO World Heritage Site.
