The automated COSC-certified PF441 chronometer movement that this Parmigiani classic runs on provides a 55-hour power reserve, owing to its oscillating mass, that is in delicately engraved gold, and can be admired with the sapphire crystal caseback. And admire it you may, as it shows some of the finest decoration https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/