The Seiko Y728-4000 is a watch model based on the Y728 movement.
Parts List
| SA3N20GM01 | crystal |
| SA3N20GM02 | crystal |
| SA3N24GM02 | crystal |
| SA3N26GM01 | crystal |
| 0C3060B04 | case back gasket |
| 86178390 | crystal gasket |
| 80612180 | pusher |
| 80612186 | pusher |
| 80612187 | pusher |
| 80612188 | pusher |
| AL414 | band - leather band |
| AL425 | band - leather band |
| AL434 | band - leather band |
| AL445 | band - leather band |
| A160CS | others - push pin |