Seiko 5Y66 is a quartz watch with a water resistance of 5 bar, making it suitable for swimming, yachting, and other aquatic sports, as well as for works closely associated with water such as kitchen work, watering, and fishing. It also has a 24-hour hand that works in conjunction with the hour hand, a retrograde day hand, and a date hand. The watch is designed to maintain stable time accuracy in normal temperatures (5℃〜35℃) and will lose or gain slightly, but it will regain high time accuracy when it returns to normal temperature.