The automatic COSC-Licensed PF441 chronometer movement that this Parmigiani classic operates on offers a 55-hour electrical power reserve, owing to its oscillating mass, which is in delicately engraved gold, and can be admired throughout the sapphire crystal caseback. And admire it you are going to, as it displays a lot https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/