The Seiko 4N21-018A is a watch model based on the 4N21 movement.
Parts List
| 200A02SN02 | crystal - crystal (sapphire) |
| 30M81DA4 | crown - crown |
| AC004BA11 | case back gasket - crown and stem gasket |
| 0F170BAA3 | case back gasket - case back gasket |
| MK22F | band - band |
| 08T25JGH | others - hour hand |
| 08T25JGM | others - minute hand |
| A130AS | others - push pin (for lb) |
| 4N210380XG14 | others - dial |
| 4N2164 | others - machine code |
| 82832715 | others - case ring |
| 4N21018A75A | others - case |
| 4N21018A | others - case back |
| 08SC653G | others - second hand |