The automatic COSC-Accredited PF441 chronometer movement that this Parmigiani classic operates on provides a 55-hour energy reserve, owing to its oscillating mass, which is in delicately engraved gold, and might be admired through the sapphire crystal caseback. And admire it you may, since it shows a few of the best https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/