The Seiko 4N21-0440 is a watch model based on the 4N21 movement.
Parts List
| 180A02SN02 | crystal - crystal (sapphire) |
| 25M25DA5 | crown - crown (3h) |
| 0F150BAA5 | case back gasket - case back gasket |
| 0H1700B01 | case back gasket - bezel gasket |
| 0F150BA1S | case back gasket - case back gasket |
| DK21E | band - band |
| WA57AB | band - band |
| WF48CW | band - band |
| 1BF050LABDG | others - hour hand |
| 2BF070LABDG | others - minute hand |
| 07SC613H | others - second hand |
| 1BA050AABNG | others - hour hand |
| 2BA075AABNG | others - minute hand |
| 3EA070A0BDG | others - second hand |
| DZ0040B01 | others - crown and stem gasket |
| 4N2104407ZB | others - case |
| 4N210440 | others - case back |
| 4N2104407ZC | others - case |
| 0351155 | others - winding stem |
| 82841070 | others - case ring |
| 4N2104407ZD | others - case |
| 4N2104407ZE | others - case |
| 4N2104407ZF | others - case |
| 4N2104407ZG | others - case |
| 4N2104407ZH | others - case |
| 4N2104407ZJ | others - case |
| 4N2104407ZA | others - case |
| 4N210890XS14 | others - dial |
| 4N210900XG14 | others - dial |
| 4N211740XS14 | others - dial |
| 4N212130XS14 | others - dial |
| 4N2164 | others - machine code |
| 82353512 | others - bezel |
| A110AS | others - push pin |
| 1BF047L1BDG | others - hour hand |
| 2BF070L1BDG | others - minute hand |
| 3DA070AABDG | others - second hand |