The Seiko 4N21-5120 is a watch model based on the 4N21 movement.
Parts List
| SA0A01SN02 | crystal - crystal |
| 6M30A3NNG1 | crown - crown |
| 0F160BAA5 | case back gasket - case back gasket |
| DK44D | band - band |
| 3BA075F1BNG | others - second hand |
| A120BS | others - push pin (for lb) |
| 4N210560XS14 | others - dial |
| 4N21512075 | others - case |
| 4N2164 | others - machine code |
| 4N21512075A | others - case |
| 4N215120 | others - case back |
| 82842630 | others - case ring |
| 06SC11NG | others - second hand |
| 1BA040A1BNG | others - hour hand |
| DZ0040B01 | others - crown and stem gasket |
| 06T03DGM | others - minute hand |
| 0351155 | others - winding stem |
| 2BA060A1BNG | others - minute hand |
| 2BA060A1BDG | others - minute hand |