Calibre 2236 Is equipped with a Syloxi hairspring that is produced by Rolex and patented. This silicon hairspring includes a patented geometry that assures the calibre’s regularity in almost any placement. Tissot traces its prolonged heritage back to 1853, when it was founded by the father-son team of Charles-Félicien Tissot https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/