The Seiko 3F31-0A20 is a watch model based on the 3F31 movement.
Parts List
| 190W36SB01 | crystal |
| 30ML0NA4 | crown |
| 0A1800N01 | case back gasket |
| AC004BAA1 | case back gasket - crown and stem gasket |
| 86574880 | crystal gasket |
| DA25BW | band - band |
| A120BS | others - push pin (for lb) |
| 3F310A20 | others - case back |
| 3F310A2075 | others - case |
| 3F310A40XS14 | others - dial |
| 3F311 | others - machine code |
| 07SC06DG | others - second hand |
| 0354735 | others - winding stem |
| 82832280 | others - case ring |
| 1AC050AMBAA | others - hour hand |
| 2AC075AMBCA | others - minute hand |