Seiko Calibre 60 movement family

Designed by Daini Seikosha. The thinnest centre-seconds watch movement in the world at 2.95 mm thick at the time of its introduction in February 1960, before the introduction of the Citizen Diamond Flake at 2.75 mm. Used in Seiko Goldfeathers. Made until ~1965.

60M, 17 jewels, found in Seiko Goldfeathers for international markets outside of Japan.

60A, 25 jewels

Found in 605010.