Calibre 2236 Is fitted that has a Syloxi hairspring that is produced by Rolex and patented. This silicon hairspring includes a patented geometry that ensures the calibre’s regularity in almost any placement. Tissot traces its extensive history back again to 1853, when it had been Launched by the father-son team https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/