The Seiko 4N21-0540 is a watch model based on the 4N21 movement.
Parts List
| 190WE5SN01 | crystal |
| 6K30A1SNG0 | crown |
| 0F175BAA1 | case back gasket |
| AC004BAA1 | case back gasket - crown and stem gasket |
| 86173930 | crystal gasket - plastic gasket for crystal |
| DA98BW | band - band |
| DAB8BW | band - leather band |
| DK30E | band - band |
| DA88BW | band - band |
| 3BA075F1BNG | others - second hand |
| 1BC052A1BAA | others - hour hand |
| A120BS | others - push pin (for lb) |
| 4N211030XS19 | others - dial |
| 4N211040XG14 | others - dial |
| 4N211620XG14 | others - dial |
| 4N2164 | others - machine code |
| 4N21054075B | others - case |
| 4N2105407HA | others - case |
| 4N21054075A | others - case |
| 4N210540 | others - case back |
| 82833515 | others - case ring |
| 0351155 | others - winding stem |
| 4N2105407HB | others - case |
| 2BA075A1BNG | others - minute hand |
| 2BC075A1BAA | others - minute hand |
| 1BA050A1BNG | others - hour hand |