The Seiko 3F31-0020 is a watch model based on the 3F31 movement.
Parts List
| 190WD1SN02 | crystal |
| 30M81DA4 | crown - crown |
| 0H1800B01 | case back gasket - case back gasket |
| AC004BA11 | case back gasket - crown and stem gasket |
| 0F170BAA3 | case back gasket - case back gasket |
| MK10G | band - leather band |
| MK11G | band - leather band |
| 07SC75JG | others - second hand |
| 0354735 | others - winding stem |
| 82833980 | others - case ring |
| 3F310020 | others - case back |
| 3F31002076A | others - case |
| 3F310020T0A | others - case |
| 3F310050XA14 | others - dial |
| 3F310050XA24 | others - dial |
| 3F310050XA34 | others - dial |
| A110AS | others - push pin |
| 1AX050ADBNG | others - hour hand |
| 2AX075ADBNG | others - minute hand |
| 190WD1SN02 | crystal |
| 30M81DA4 | crown - crown |
| 0H1800B01 | case back gasket - case back gasket |
| AC004BA11 | case back gasket - crown and stem gasket |
| 0F170BAA3 | case back gasket - case back gasket |
| MK10G | band - leather band |
| MK11G | band - leather band |
| 07SC75JG | others - second hand |
| 0354735 | others - winding stem |
| 82833980 | others - case ring |
| 3F310020 | others - case back |
| 3F31002076A | others - case |
| 3F310020T0A | others - case |
| 3F310050XA14 | others - dial |
| 3F310050XA24 | others - dial |
| 3F310050XA34 | others - dial |
| A110AS | others - push pin |
| 1AX050ADBNG | others - hour hand |
| 2AX075ADBNG | others - minute hand |