Calibre 2236 Is equipped using a Syloxi hairspring that is made by Rolex and patented. This silicon hairspring contains a patented geometry that assures the calibre’s regularity in almost any position. 6 miles, or 55.7 km) at the conclusion of a 6 months’ voyage. (The geographical mile is defined as https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/