The automated COSC-Accredited PF441 chronometer movement that this Parmigiani basic operates on offers a fifty five-hour energy reserve, owing to its oscillating mass, which happens to be in delicately engraved gold, and may be admired from the sapphire crystal caseback. And admire it you can, as it shows a lot https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/