The Precision of a Rolex Superlative Chronometer is with the buy of −2/+2 seconds per day – the speed deviation tolerated via the brand name for any completed check out is appreciably scaled-down than that recognized by COSC for Formal certification of the motion by itself. The Superlative Chronometer status https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/