Calibre 2236 Is fitted that has a Syloxi hairspring that is produced by Rolex and patented. This silicon hairspring has a patented geometry that makes certain the calibre’s regularity in any position. The third major phase took place inside the early 1900’s. The form from the timekeeping apparatus adjusted in https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/