Calibre 2236 Is fitted that has a Syloxi hairspring that is produced by Rolex and patented. This silicon hairspring features a patented geometry that guarantees the calibre’s regularity in any posture. In conjunction with his colleague Thomas Earnshaw, the pair would build simplified and sensible marine chronometers. In Doxa's modern-day https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/