The automatic COSC-certified PF441 chronometer motion that this Parmigiani typical operates on offers a 55-hour electricity reserve, owing to its oscillating mass, and that is in delicately engraved gold, and can be admired through the sapphire crystal caseback. And admire it you are going to, since it shows a lot https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/