Yema CMM.20

The CMM.20 — Calibre Manufacture Morteau — debuted in late 2022 in a limited-edition Wristmaster Traveller Micro-Rotor, marking Yema's move into its Manufacture-grade CMM caliber program rather than its first caliber-development effort. The movement was designed by independent watchmaker Olivier Mory of OM Mechanics (La Chaux-de-Fonds), with mainplates and bridges produced at Yema's own workshops in Morteau, France, and the regulating organs sourced from Switzerland. Yema characterizes the supply chain as approximately 80% French and 20% Swiss.

The movement's defining architectural choice is a bi-directional micro-rotor in high-density tungsten alloy, which compresses total height to 3.70 mm — about 20% slimmer than an ETA 2824-2 — without sacrificing a generous 70-hour power reserve. The Glucydur balance wheel, Incabloc shock absorption, and ETACHRON regulator are well-proven Swiss-standard components rather than novel engineering; the architecture as a whole is a ground-up commission, not derived from any existing ebauche.

Since its launch the CMM.20 has been deployed across several Yema families — Superman Slim, Navygraf Slim, Skin Diver Slim, Wristmaster Slim, and Granvelle — establishing it as the brand's platform manufacture caliber. Its regulated accuracy of minus 3 to plus 7 seconds per day approaches but does not reach COSC chronometer tolerances. The CMM.20 does not hack while running; Yema's operating instructions describe a workaround for seconds synchronization from a stopped/unwound state.

The CMM.20 plays in the accessible manufacture tier alongside movements such as the Oris Calibre 400 and Tudor MT5400, but at a considerably lower price. Its appeal rests on slim dimensions, a strong power reserve, and the credibility of genuine near-in-house manufacture for a French brand that had long relied on Swiss ebauches from ETA and Valjoux.