A recent advance in Seiko in-house mechanical timekeeping Calibers 6R55 and 6R5J have an astounding power reserve of 72 hours (3 full days) once fully wound. Prominently featured within the Presage Luxe and King Seiko collections, each beats at 21,600 vph and is equipped with 24 jewels. 6R55 offers a date calendar complication while 6R5J offers a 24-hour display and allows a view of mechanical timekeeping in action when paired with an open-aperture dial.