The Seiko 4N21-5040 is a watch model based on the 4N21 movement.
Parts List
| ESFW37SN01 | crystal |
| 25M25DA5 | crown - crown (3h) |
| 0H1900B01 | case back gasket - case back gasket |
| 0F180BAA1 | case back gasket - case back gasket |
| DB38A | band - metal band |
| 1BF045L0BDG | others - hour hand |
| 2BF065L0BDG | others - minute hand |
| DZ0040B01 | others - crown and stem gasket |
| 0351155 | others - winding stem |
| 06T21DGH | others - hour hand |
| 06SC19VG | others - second hand |
| 81606439 | others - bracelet fixing pin |
| 81181459 | others - bracelet fixing pipe |
| 81607079 | others - bracelet fixing pin |
| 4N210200XS19 | others - dial |
| 4N215040 | others - case back |
| 4N215040SFA | others - case |
| 4N2164 | others - machine code |
| 82343571 | others - bezel |
| 82841370 | others - case ring |
| 06T21DGM | others - minute hand |