The Seiko 4N21-5410 is a watch model based on the 4N21 movement.
Parts List
| K01A77SN02 | crystal - crystal |
| 6K40A6SNWB | crown - crown |
| 6K40A6SNWD | crown - crown |
| 0F160BAA1 | case back gasket |
| D135AQ | band - band |
| D135AQ-LK00 | band - link |
| D135AQ-BK00 | clasp - clasp |
| 3BA075F1BA6 | others - second hand |
| 3BA075F1BNS | others - second hand |
| 2BG055LABDS | others - minute hand |
| 1BG037LABDS | others - hour hand |
| 0351155 | others - winding stem |
| 81190075 | others - bracelet fixing pipe |
| 81604219 | others - bracelet fixing pin |
| 82835450 | others - case ring |
| 4N21541061A | others - case |
| 4N215410 | others - case back |
| 4N212530XA13 | others - dial |
| 4N212540XS19 | others - dial |
| 4N21541061B | others - case |
| 4N2165 | others - machine code |
| D135AQ-BKPP | others - spring bar for buckle/clasp |
| D135AQ-LKPN | others - pin for link |
| EZ0035B01 | others - crown and stem gasket |