The Precision of the Rolex Superlative Chronometer is of the order of −two/+2 seconds a day – the rate deviation tolerated with the model to get a completed look at is appreciably scaled-down than that accepted by COSC for official certification of the movement by yourself. The Superlative Chronometer position https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/