The Seiko Y661-4020 is a watch model based on the Y661 movement.
Parts List
| SABN59LM10 | crystal |
| SABN59LM40 | crystal |
| 35M59NS1 | crown |
| 35M59NN1 | crown |
| 010110B01 | case back gasket |
| EB0055B01 | others - crown and stem gasket |
Other models with the same movement
| Y661-4010 |
| Y661-4030 |