The Seiko 7017A watch movement, produced between 1949-1950, was the first gents automatic-family movement featuring a ball-bearing rotor. This movement underwent modifications, including a change from T- to U shock device and a modified calibre, resulting in various variants. The availability of all calibres in the TC variant remains unknown. Furthermore, the signatures of UT versions were changed to UC. The movement features a sweep second hand and operates on automatic winding.