The Precision of the Rolex Superlative Chronometer is with the purchase of −two/+2 seconds on a daily basis – the speed deviation tolerated because of the model for just a finished watch is drastically scaled-down than that accepted by COSC for Formal certification of your motion alone. The Superlative Chronometer https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/