CHRONOSWISS C121 Brand CHRONOSWISS Caliber C121 Size Function Version Hands Stem Stem (subs.) Stem (2 pce) Balance staff Balance staff (subs.) Mainspring (subs.) 1.35x10.0x0.11 Mainspring (subs.) Ersatz: 820 3315 0 Battery WatchpartsPart NocaliberdescriptionoriginalArtno.771Mainspring AUT sliding attachemnet99900771C121