The Seiko 4N21-5250 is a watch model based on the 4N21 movement.
Parts List
| RE3A25SN02 | crystal - crystal |
| 40M0CNA6 | crown |
| 40M0CNK1 | crown - crown |
| 6M40B1SNW0 | crown - crown |
| 40N0CNA6 | crown |
| 6M40B1SNG0 | crown - crown |
| 0F180BA1S | case back gasket - case back gasket |
| DAT9BW | band - band |
| DAV3BB | band - leather band |
| DAZ6AW | band - band |
| 2BA055A1BAK | others - minute hand |
| 3BA075F1BA6 | others - second hand |
| 1BA037A1BAK | others - hour hand |
| A120BS | others - push pin (for lb) |
| 4N211910XS14 | others - dial |
| 4N211910XS24 | others - dial |
| 4N2164 | others - machine code |
| 4N21525071A | others - case |
| 82871350 | others - case ring |
| 4N215250 | others - case back |
| 4N21525075A | others - case |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |