The Seiko M421-502A is a watch model based on the M421 movement.
Parts List
| ES8W93LN00 | crystal |
| FH2980B0B | case back gasket |
| EA0090B0A | case back gasket - button gasket |
| 80608834 | pusher |
Other models with the same movement
| M421-5000 |
| M421-500A |
| M421-5010 |
| M421-5020 |
| M421-5030 |