The automated COSC-Qualified PF441 chronometer movement that this Parmigiani vintage runs on provides a fifty five-hour energy reserve, owing to its oscillating mass, that is in delicately engraved gold, and can be admired from the sapphire crystal caseback. And admire it you might, because it shows some of the best https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/