The Seiko 4N21-5280 is a watch model based on the 4N21 movement.
Parts List
| SA2A23SN02 | crystal - crystal |
| 6M35B3NNG1 | crown |
| 6M35B3SNG0 | crown - crown |
| 6M35D7SNG0 | crown - crown |
| 0F150BA1S | case back gasket - case back gasket |
| D0N9AQ | band - band |
| D0N9FQ | band - band |
| D0N9AQ-LK00 | band - link |
| D0N9FQ-LK00 | band - link |
| D0N9FQ-BK00 | clasp - clasp |
| D0N9AQ-BK00 | clasp - clasp |
| 3BA075F1BNG | others - second hand |
| 1BC037A1BNG | others - hour hand |
| 2BC055A1BNG | others - minute hand |
| 2BH052AABNG | others - minute hand |
| 82834230 | others - case ring |
| 4N215280 | others - case back |
| 4N212080XG14 | others - dial |
| 4N212090XS14 | others - dial |
| 4N21528075A | others - case |
| 4N2152807EA | others - case |
| 4N2164 | others - machine code |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |
| D0N9FQ-LKPN | others - pin for link |
| T090AS | others - push pin |
| D0N9AQ-LKPN | others - pin for link |