The Seiko 4N21-5240 is a watch model based on the 4N21 movement.
Parts List
| RE2A89SN02 | crystal |
| 6M30B5NNG1 | crown - crown |
| 0F160BAA5 | case back gasket - case back gasket |
| DAN4BW | band - band |
| DAN5BW | band - band |
| 3BA075F1BNG | others - second hand |
| 2BC055A1BNG | others - minute hand |
| 1BC035A1BNG | others - hour hand |
| 1BF040A1BNG | others - hour hand |
| A110BS | others - push pin (for mb) |
| 4N211600XS14 | others - dial |
| 4N211610XS14 | others - dial |
| 4N215240 | others - case back |
| 4N2152407NA | others - case |
| 4N2164 | others - machine code |
| 82863570 | others - case ring |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |
| 2BF060A1BNG | others - minute hand |