The Seiko 4N00-5121 is a watch model based on the 4N00 movement.
Parts List
| SAJN39JN01 | crystal - crystal |
| SAJN39JN | crystal |
| 35MM3NN1 | crown |
| 0H1700B01 | case back gasket - bezel gasket |
| 0H1700B0 | case back gasket |
| AC004BA11 | case back gasket - crown and stem gasket |
| 4F48YZ | band - leather band |
| 1CE035L0BDG | others - hour hand |
| 2CE052L0BDG | others - minute hand |
| 05Y09NGM | others - minute hand |
| 05Y05NGH | others - hour hand |
| 4N00512125 | others - case |
| 82841470 | others - case ring |
| 4N005121 | others - case back |
| 0351155 | others - winding stem |
| 4N000301XB14 | others - dial |
| 4N000301XG14 | others - dial |
| 4N0061 | others - machine code |
| A110AS | others - push pin |