The Seiko 4N00-0421 is a watch model based on the 4N00 movement.
Parts List
| 180A02JN02 | crystal - crystal |
| 180A02JN | crystal |
| 6M30A3NNG0 | crown - crown |
| 6M30A3NN | crown |
| 0H1700B01 | case back gasket - bezel gasket |
| 0H1700B0 | case back gasket |
| Q5056K | band |
| Q5056K-LKG | band - link |
| Q5056K-BK4G | clasp - clasp |
| 2CA075A1BNG | others - minute hand |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |
| 81181459 | others - bracelet fixing pipe |
| 81607199 | others - bracelet fixing pin |
| 82841070 | others - case ring |
| 4N000421 | others - case back |
| 4N000421CH | others - case |
| 4N001591XS14 | others - dial |
| 4N0061 | others - machine code |
| Q5056K-EPG | others - endpiece |
| 1CA050A1BNG | others - hour hand |