The Seiko 1F21-5B90 is a watch model based on the 1F21 movement.
Parts List
| RE1A18SR02 | crystal - crystal |
| 30MA2NS1 | crown - crown |
| 0F180NA1S | case back gasket - case back gasket |
| DAW4AW | band - band |
| 1BC035A1BAF | others - hour hand |
| 3BA075F1BNS | others - second hand |
| 2BC052A1BAF | others - minute hand |
| 0351807 | others - winding stem |
| 1F215B907E | others - case |
| 82836120 | others - case ring |
| 1F215B90 | others - case back |
| 1F211F10XS19 | others - dial |
| 1F215 | others - machine code |
| A120AS | others - push pin |
| EZ0035B01 | others - crown and stem gasket |