Calibre 2236 Is fitted using a Syloxi hairspring that is made by Rolex and patented. This silicon hairspring contains a patented geometry that makes sure the calibre’s regularity in any placement. In conjunction with his colleague Thomas Earnshaw, the pair would establish simplified and functional maritime chronometers. Some say “cosk” https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/