The automatic COSC-Licensed PF441 chronometer motion that this Parmigiani traditional runs on provides a 55-hour electricity reserve, owing to its oscillating mass, which is in delicately engraved gold, and may be admired through the sapphire crystal caseback. And admire it you'll, as it shows a lot of the best decoration https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/