Product Description: SEIKO SPORTSMATIC CALENDER 820 Vintage from the 1960s. Approximately 37cm wide and 40cm long. Overhauled at the end of last year. The crystal has been polished. The daily rate is about -15 to -20 seconds. Although it's often said to be prone to issues, the date function on this model only changes at 12 o'clock and doesn't have a quick-set feature. It's an automatic watch only, with no manual winding function. The case has some rust, but it has been removed as much as possible. The crown is original, and the strap is aftermarket, so you might consider changing it to a leather strap. The current wrist size is about 17cm. It's an old watch, but it has been overhauled, so you should be able to use it for several years with care, avoiding water exposure.