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