The automatic COSC-certified PF441 chronometer movement that this Parmigiani classic runs on offers a 55-hour energy reserve, owing to its oscillating mass, which can be in delicately engraved gold, and will be admired from the sapphire crystal caseback. And admire it you can, as it shows several of the best https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/