Calibre 2236 Is fitted which has a Syloxi hairspring that is made by Rolex and patented. This silicon hairspring incorporates a patented geometry that makes certain the calibre’s regularity in almost any position. James L. January 14, 2023 The explanation I say that I am surprised is because of Certina https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/