The Precision of the Rolex Superlative Chronometer is of your purchase of −2/+2 seconds on a daily basis – the rate deviation tolerated because of the model for any concluded watch is appreciably scaled-down than that approved by COSC for Formal certification on the movement by yourself. The Superlative Chronometer https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/