The Seiko S640-4020 is a watch model based on the S640 movement.
Parts List
| ES0P35H20A | crystal - crystal |
| ES0P35H2 | crystal |
| 0F370BEA1 | case back gasket - case back gasket |
| 0F370BEA | case back gasket |
| 86600830 | crystal gasket - plastic gasket for crystal |
| 80632219 | pusher - button(10h) |
| 80632110 | pusher - button (4h) |
| 80632130 | pusher - button (8h) |
| 80632090 | pusher - button |
| 4FL3AB | band - band |
| 4FP4JB | band - band |
| 86510695 | others - conducting plate |
| S64010 | others - machine code |
| T120BS | others - push pin |
| 81514639 | others - case back screw |
| 81351630 | others - button spring |
| AD006BA11 | others - crown and stem gasket |
| 81351859 | others - button spring (front) |
| 81351879 | others - button spring(other pos.) |
| S6404020N2A | others - case |
| S6404020 | others - case back |
| S6404020N2B | others - case |
| 83200211 | others - button spring clip |
Other models with the same movement