The Seiko 4N20-0640 is a watch model based on the 4N20 movement.
Parts List
| 175A02SN02 | crystal - crystal |
| 25M25DA5 | crown - crown (3h) |
| 25M25NS5 | crown - crown |
| 0H1600B01 | case back gasket - case back gasket |
| DZ36B | band - metal band |
| DZ37B | band - metal band |
| 05Y07JGH | others - hour hand |
| 05Y07JGM | others - minute hand |
| 2CG055L0BDS | others - minute hand |
| 05Y07JSH | others - hour hand |
| 1CG037L0BDS | others - hour hand |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |
| 81181459 | others - bracelet fixing pipe |
| 81604259 | others - bracelet fixing pin |
| 81601489 | others - bracelet fixing pin |
| 82841030 | others - case ring |
| 4N200640 | others - case back |
| 4N2006402EA | others - case |
| 4N200640FYA | others - case |
| 4N201140XS15 | others - dial |
| 4N2061 | others - machine code |
| 89942935 | others - back plate |
| 05Y07JSM | others - minute hand |
| 2CG055L0BDG | others - minute hand |
| 1CG037L0BDG | others - hour hand |