Calibre 2236 Is equipped using a Syloxi hairspring that is made by Rolex and patented. This silicon hairspring has a patented geometry that assures the calibre’s regularity in almost any place. six miles, or fifty five.7 km) at the end of a 6 weeks’ voyage. (The geographical mile is defined https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/