The Seiko 3M21-0A20 is a watch model based on the 3M21 movement.
Parts List
| 280W32SN00 | crystal - crystal |
| 8M35A4SNGA | crown - crown |
| 0F230NA1S | case back gasket - case back gasket |
| EG0115B01 | case back gasket - button gasket |
| 86567260 | crystal gasket |
| 86571020 | bezel gasket - plastic gasket for bezel |
| 80604609 | pusher - button |
| D039CM | band - band |
| D069DB | band - band |
| D069EB | band - band |
| D069DB-BK00 | clasp - clasp |
| 10ST04DG | others - second hand |
| 1BB075A4BAF | others - hour hand |
| 1BB075A4BAJ | others - hour hand |
| 2BB100A2BCF | others - minute hand |
| 2BB100A2BCJ | others - minute hand |
| 0351550 | others - winding stem |
| 82835760 | others - case ring |
| 3M210A2098 | others - case |
| 82287704 | others - bezel |
| 3M210A20 | others - case back |
| 3M210A2098A | others - case |
| 82835765 | others - case ring |
| 3M210A20XB14 | others - dial |
| 3M210A20XS14 | others - dial |
| 3M210A70XS14 | others - dial |
| 3M210A90XS14 | others - dial |
| 3M211 | others - machine code |
| A170BS | others - push pin |
| 81355429 | others - button spring |
| 81400709 | others - button spring clip |
| AD006BA12 | others - crown gasket |
Other models with the same movement