The Seiko 1F21-5B20 is a watch model based on the 1F21 movement.
Parts List
| SACW46SN01 | crystal - crystal |
| 6K30A0SNG1 | crown |
| 6K30A0SNW1 | crown - crown |
| 0F180NA1S | case back gasket - case back gasket |
| 0A1800N01 | case back gasket |
| 0F180BA1S | case back gasket - case back gasket |
| 86582320 | crystal gasket - plastic gasket for crystal |
| DA68AW | band - band |
| MK52F | band - band |
| DA78BW | band - band |
| DA68BW | band - band |
| DA68AW-BJ00 | clasp - buckle |
| DA78BW-BJ00 | clasp - buckle |
| 1BB042A2BAC | others - hour hand |
| 1BB042A2BAD | others - hour hand |
| 2BB065A0BCC | others - minute hand |
| 2BB065A0BCD | others - minute hand |
| 3BA080F0BNS | others - second hand |
| 1F215B2071 | others - case |
| 82832240 | others - case ring |
| 1F215B20 | others - case back |
| 1F215B2071A | others - case |
| 1F215B2071B | others - case |
| 1F215B2075 | others - case |
| 0351807 | others - winding stem |
| 1F215B2075A | others - case |
| 1F215B2075B | others - case |
| 1F215B20SA | others - case |
| 1F215B20SAC | others - case |
| 1F215B20SAD | others - case |
| 1F215B20SAE | others - case |
| 1F215B20SAF | others - case |
| 1F210K30XG14 | others - dial |
| 1F210K30XS14 | others - dial |
| 1F210K30XS23 | others - dial |
| 1F215 | others - machine code |
| 1F21A | others - machine code |
| 1F21HAC0HS14 | others - dial |
| A120AS | others - push pin |
| EZ0035B01 | others - crown and stem gasket |
| 3BA080F0BNG | others - second hand |