The Seiko 4J81-0B20 is a watch model based on the 4J81 movement.
Parts List
| 180W30SB01 | crystal - crystal |
| 36M06NE2 | crown |
| 36M06NS2 | crown - crown (3h) |
| 0F180BAD2 | case back gasket - case back gasket |
| 86580060 | crystal gasket - plastic gasket for crystal |
| A083CZ | band - band |
| A087AB | band - band |
| A083CB | band - metal band |
| 07ST08JS | others - second hand |
| 1BB045Y0BHS | others - hour hand |
| 2BB070Y0BHS | others - minute hand |
| 07ST08JG | others - second hand |
| 1BB045Y0BHG | others - hour hand |
| 2BB070Y0BHG | others - minute hand |
| 0351405 | others - winding stem |
| 81606439 | others - bracelet fixing pin |
| 81190055 | others - bracelet fixing pipe |
| 81190875 | others - bracelet fixing pipe |
| 82835740 | others - case ring |
| 4J810B2001 | others - case |
| 4J810B20 | others - case back |
| 4J810B2002 | others - case |
| 4J810B2003 | others - case |
| EA0040B0A | others - crown and stem gasket |