HATTORY-SEIKO 21A Exploded diagram Brand HATTORY-SEIKO Caliber 21A Size Function Version Hands Stem 351-211 Stem (subs.) Stem (2 pce) Balance staff 351-120 Balance staff (subs.) Mainspring (subs.) Mainspring (subs.) Battery WatchpartsPart NocaliberdescriptionoriginalArtno.721Balance cplt. -regulated310-2109840310210