The Seiko 4N21-5210 is a watch model based on the 4N21 movement.
Parts List
| SA0P09SN03 | crystal |
| 6K30A1SNG0 | crown |
| 0F175BAA5 | case back gasket - case back gasket |
| 0F180BAA3 | case back gasket |
| AC004BAA1 | case back gasket - crown and stem gasket |
| 86600010 | crystal gasket |
| KB03A | band - metal band |
| 3BA075F1BNG | others - second hand |
| 1BF040A1BNG | others - hour hand |
| A120BS | others - push pin (for lb) |
| 4N211250XS14 | others - dial |
| 4N215210 | others - case back |
| 4N21521098 | others - case |
| 4N2164 | others - machine code |
| 82862190 | others - case ring |
| 0351155 | others - winding stem |
| 2BF060A1BNG | others - minute hand |