The Seiko 4N21-0380 is a watch model based on the 4N21 movement.
Parts List
| 185W55SK01 | crystal - crystal |
| 30M81NA4 | crown - crown |
| 0H1700B01 | case back gasket - bezel gasket |
| 0F160BAA5 | case back gasket - case back gasket |
| AC004BA11 | case back gasket - crown and stem gasket |
| DK06E | band - band |
| 3BA075F1BNG | others - second hand |
| 07T61CGH | others - hour hand |
| 07T61CGM | others - minute hand |
| A110BS | others - push pin (for mb) |
| 4N210770XG14 | others - dial |
| 4N2164 | others - machine code |
| 0351155 | others - winding stem |
| 4N21038075A | others - case |
| 82353051 | others - bezel |
| 4N210380 | others - case back |
| 82833515 | others - case ring |