The Seiko 6309A watch movement, produced from 1975 onwards, features a micrometer regulator and two serially coupled stacked barrels. One of the barrels contains a fixed spring, while the other utilizes a slip spring. The distinctions between the 890 and 890.1 variations remain undisclosed. This movement incorporates several functions, including automatic winding, a sweep seconds hand, a quickset date feature, and a hack feature.