The Precision of a Rolex Superlative Chronometer is in the purchase of −two/+two seconds a day – the rate deviation tolerated because of the model for the completed check out is drastically scaled-down than that acknowledged by COSC for Formal certification in the movement by yourself. The Superlative Chronometer position https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/