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