Seiko is one of the few completely-integrated manufactures of watches.
As with Seiko's watches, there were two “streams” of movements from the two Seiko watch companies, Suwa and Daini.
As with Seiko's watches, there were two “streams” of movements from the two Seiko watch companies, Suwa and Daini, and frequently two more streams, 26 mm and a larger size nearer to 28 mm.
Seiko's basic automatics are marked by slower speed (18,000 or 21,600), less features than contemporaries (hacking, hand-winding, complications), fewer jewels, and use in budget models.
Seiko's midrange movements are characterized by better performance and use in higher-end models.