The automatic COSC-Qualified PF441 chronometer movement that this Parmigiani typical runs on offers a 55-hour electrical power reserve, owing to its oscillating mass, that's in delicately engraved gold, and may be admired from the sapphire crystal caseback. And admire it you will, as it displays many of the greatest decoration https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/