Calibre 2236 Is fitted which has a Syloxi hairspring that is made by Rolex and patented. This silicon hairspring has a patented geometry that guarantees the calibre’s regularity in almost any posture. There you've got it, five brands that have performed a large part in the development from the chronograph. https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/