The automated COSC-Qualified PF441 chronometer movement that this Parmigiani classic runs on offers a 55-hour electrical power reserve, owing to its oscillating mass, which happens to be in delicately engraved gold, and may be admired with the sapphire crystal caseback. And admire it you will, as it shows a number https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/