The Seiko Y131-6640 is a watch model based on the Y131 movement.
Parts List
| 35MS4NC1 | crown |
| 35MS4NF1 | crown |
| 35MP0NS1 | crown |
| 0A2400B01 | case back gasket |
| 067LDB | band |
| 079LDB | band |
| EG0060B01 | others - button gasket |
| 0354786 | others - winding stem |
| 02SC02TG | others - second hand |
| 11C36ASM | others - minute hand |
| 10C62AYM | others - minute hand |
| 11C36ASH | others - hour hand |
| 10C62ARH | others - hour hand |