The Precision of the Rolex Superlative Chronometer is on the order of −two/+2 seconds each day – the speed deviation tolerated from the brand for any finished look at is noticeably scaled-down than that recognized by COSC for Formal certification of your movement on your own. The Superlative Chronometer status https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/