The automated COSC-Licensed PF441 chronometer motion that this Parmigiani classic runs on offers a 55-hour energy reserve, owing to its oscillating mass, that is in delicately engraved gold, and can be admired through the sapphire crystal caseback. And admire it you might, because it displays several of the greatest decoration https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/