Seiko 5 Sports Skx Mid-Size. With vintage styling and colors recalling the quartz diver's watches of the 1980s, the mid-size Skx design offers the 38mm case diameter of the originals, but with a slimmer case and a durable, yet comfortable, three-row sport bracelet. Providing automatic technology that you control with every movement, this dynamic timepiece is powered by a 24-jewel movement that beats at a frequency of 21,600 vibrations per hour, with a power reserve of approximately 41 hours and manual winding capability.