Hamilton H40655131 American Classic RailRoad Skeleton AutoProduct Overview A design that honors Hamilton's glorious history, known as "The Watch of Railroad Accuracy" from the 19th century. The H 10 S movement boasts an astonishing standard power reserve of 80 hours, adding functionality and strength to its classic design. The skeleton style allows you to fully enjoy the movement's mechanics. Specifications Product Number H40655131 Caliber H 10 S Collection American Classic Movement Automatic Case Size 42mm