The Seiko 4N21-5310 is a watch model based on the 4N21 movement.
Parts List
| SA2A43SN02 | crystal - crystal |
| 6M35A2SNGB | crown - crown |
| 6M35A2SNWD | crown - crown |
| 0F150BA1S | case back gasket - case back gasket |
| D0Q9AB | band - band |
| D0Q9BB | band - band |
| 1BC040A1BAL | others - hour hand |
| 1BH042A1BAL | others - hour hand |
| 2BC060A1BAL | others - minute hand |
| 2BH060A1BAL | others - minute hand |
| 3BA075F1BA6 | others - second hand |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |
| 4N21531076A | others - case |
| 82835290 | others - case ring |
| 81605381 | others - bracelet fixing pin |
| 4N215310 | others - case back |
| 4N2153107EA | others - case |
| 81605389 | others - bracelet fixing pin |
| 4N212150XA14 | others - dial |
| 4N212160XS19 | others - dial |
| 4N2164 | others - machine code |
| 81503021 | others - screw |
| 81503029 | others - screw |
| 89942935 | others - back plate |