The automatic COSC-Licensed PF441 chronometer movement that this Parmigiani common operates on offers a 55-hour electrical power reserve, owing to its oscillating mass, which happens to be in delicately engraved gold, and might be admired from the sapphire crystal caseback. And admire it you might, as it shows a number https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/