The Seiko 4M21-0A40 is a watch model based on the 4M21 movement.
Parts List
| 280P18SR01 | crystal |
| 8K45B6TTA1 | crown - crown |
| 0F260NA1S | case back gasket - case back gasket |
| 86580520 | crystal gasket - plastic gasket for crystal |
| EC0060B01 | pusher - pusher gasket |
| 80601367 | pusher - button |
| D0M2AM | band - band |
| 12ST08CS | others - second hand |
| 1BB080A2BAK | others - hour hand |
| 2BB120A2BCK | others - minute hand |
| 81400709 | others - button spring clip |
| 81350540 | others - button spring |
| 0351552 | others - winding stem |
| 81504044 | others - decorative bezel fixing screw |
| 82837200 | others - case ring |
| 4M210A40XD | others - case |
| 82289824 | others - bezel |
| 4M210A50XB13 | others - dial |
| 4M216 | others - machine code |
| A140BS | others - push pin |
| 81400829 | others - button spring clip |
| 0Z0060B01 | others - crown and stem gasket |
Caliber 4M21
Other models with the same movement
| 4M21-0010 |
| 4M21-0A10 |
| 4M21-0A20 |
| 4M21-0A30 |
| 4M21-0A50 |
| 4M21-0A60 |
| 4M21-0A70 |
| 4M21-0A80 |
| 4M21-0A90 |
| 4M21-0B00 |
| 4M21-0B0A |
| 4M21-0B10 |
| 4M21-0B20 |
| 4M21-0B30 |
| 4M21-0B40 |
| 4M21-0B50 |
| 4M21-0B60 |
| 4M21-0B70 |
| 4M21-0B80 |
| 4M21-0B90 |
| 4M21-0C00 |
| 4M21-0C10 |