The Precision of a Rolex Superlative Chronometer is on the purchase of −2/+two seconds a day – the speed deviation tolerated via the manufacturer to get a completed watch is substantially scaled-down than that accepted by COSC for Formal certification from the motion alone. The Superlative Chronometer position is symbolized https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/