The Seiko 5E31-5B20 is a watch model based on the 5E31 movement.
Parts List
| SACW30SK01 | crystal |
| 25M20NA3 | crown |
| 0A2600N01 | case back gasket - case back gasket |
| AB45B | band - metal band |
| 0351624 | others - winding stem |
| 12ST06DA | others - second hand |
| 81180229 | others - bracelet fixing pipe |
| 81604259 | others - bracelet fixing pin |
| 5E315 | others - machine code |
| 5E315B20 | others - case back |
| 5E315B20SF | others - case |
| 5E315B50XS14 | others - dial |
| 82830560 | others - case ring |
| 87020283 | others - back plate |
| 1BB065L0BCA | others - hour hand |
| EZ0035B01 | others - crown and stem gasket |
| 2BB100L0BCA | others - minute hand |