The Precision of the Rolex Superlative Chronometer is with the buy of −two/+2 seconds each day – the rate deviation tolerated via the manufacturer for just a completed watch is noticeably smaller than that accepted by COSC for Formal certification from the movement alone. The Superlative Chronometer position is symbolized https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/