The Seiko 4J81-0A20 is a watch model based on the 4J81 movement.
Parts List
| 180W30SN01 | crystal |
| 36M06NE2 | crown |
| 0F180NAAS | case back gasket - case back gasket |
| 86580060 | crystal gasket - plastic gasket for crystal |
| AA21BW | band - band |
| Z01YJ-BK00 | clasp - clasp |
| 07ST08JG | others - second hand |
| 1BB045Y0BHG | others - hour hand |
| 2BB070Y0BHG | others - minute hand |
| A120BS | others - push pin (for lb) |
| 4J810A2093 | others - case |
| 82835720 | others - case ring |
| 0351405 | others - winding stem |
| EA0040B0A | others - crown and stem gasket |