The Seiko Y131-6440 is a watch model based on the Y131 movement.
Parts List
| 35MT0N11 | crown |
| 35MT0NG1 | crown |
| 35MT0NP1 | crown |
| 0A2200B01 | case back gasket - case back gasket |
| 267LB | band - leather band |
| 271LB | band - leather band |
| 327LB | band - leather band |
| 329LB | band - leather band |
| 331LB | band - leather band |
| 333LB | band - leather band |
| 0354786 | others - winding stem |
| 10CP2NBM | others - minute hand |
| 10CP2AWM | others - minute hand |
| 10CP2AWH | others - hour hand |
| 12SC50XW | others - second hand |
| 10CP2NBH | others - hour hand |
| AD006BA12 | others - crown gasket |
| 12SC50FB | others - second hand |
| 10CP6NBH | others - hour hand |