Calibre 2236 Is equipped that has a Syloxi hairspring that is produced by Rolex and patented. This silicon hairspring provides a patented geometry that makes certain the calibre’s regularity in any place. In conjunction with his colleague Thomas Earnshaw, the pair would produce simplified and practical maritime chronometers. Roger Dubuis https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/