The Seiko 1F21-0B20 is a watch model based on the 1F21 movement.
Parts List
| 205W14SN01 | crystal |
| 35MC2NS1 | crown - crown |
| 0A2000N0A | case back gasket |
| 86580720 | crystal gasket - plastic gasket for crystal |
| DL18B | band - leather band |
| A110BS | others - push pin (for mb) |
| 1F210B20 | others - case back |
| 1F210B2061 | others - case |
| 1F210C20XS13 | others - dial |
| 1F219 | others - machine code |
| 82821720 | others - case ring |
| 0351807 | others - winding stem |
| 08TJ0DBH | others - hour hand |
| 08TJ0DBM | others - minute hand |
| EA0040B0A | others - crown and stem gasket |
| 12SC36TB | others - second hand |