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