Calibre 2236 Is equipped having a Syloxi hairspring that is made by Rolex and patented. This silicon hairspring features a patented geometry that guarantees the calibre’s regularity in any situation. ZENITH launches the 135-Observatoire confined version, earning the acclaimed one hundred thirty five calibre, serial winner in the Intercontinental Chronometry https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/