The Precision of a Rolex Superlative Chronometer is with the purchase of −two/+two seconds per day – the speed deviation tolerated by the manufacturer for any completed view is considerably scaled-down than that approved by COSC for Formal certification on the movement by itself. The Superlative Chronometer status is symbolized https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/