The automatic COSC-Accredited PF441 chronometer movement that this Parmigiani classic operates on provides a fifty five-hour electrical power reserve, owing to its oscillating mass, that's in delicately engraved gold, and may be admired through the sapphire crystal caseback. And admire it you can, as it displays many of the best https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/