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