The Seiko 3F31-0C20 is a watch model based on the 3F31 movement.
Parts List
| 200P01SN02 | crystal |
| 30MK8NA4 | crown - crown |
| 0F180NA1S | case back gasket - case back gasket |
| 86580100 | crystal gasket - plastic gasket for crystal |
| WB59BW | band - band |
| 3F310C2076 | others - case |
| 82833980 | others - case ring |
| 3F310B30XS19 | others - dial |
| 3F311 | others - machine code |
| 87020760 | others - back plate |
| A120AS | others - push pin |
| 0354735 | others - winding stem |
| EZ0035B01 | others - crown and stem gasket |
| 08SC22D1 | others - second hand |
| 1BC055A1BNG | others - hour hand |
| 2AC080A1BDG | others - minute hand |