The Seiko 4N21-0310 is a watch model based on the 4N21 movement.
Parts List
| 130P01SN03 | crystal |
| 6K45A1SNG1 | crown |
| 0F155BAA3 | case back gasket - case back gasket |
| AC004BAA1 | case back gasket - crown and stem gasket |
| 86593310 | crystal gasket |
| 86593290 | bezel gasket |
| TB14A | band - metal band |
| TB16A | band - metal band |
| 3BA075F1BNG | others - second hand |
| A120BS | others - push pin (for lb) |
| 4N210310 | others - case back |
| 4N21031075 | others - case |
| 4N21031098 | others - case |
| 4N210700XS14 | others - dial |
| 4N210700XZ14 | others - dial |
| 4N2164 | others - machine code |
| 82352631 | others - bezel |
| 1BX035FABAA | others - hour hand |
| 0351155 | others - winding stem |
| 82840910 | others - case ring |
| 2BA052SABDG | others - minute hand |