The Seiko 3B21-0AD0 is a watch model based on the 3B21 movement.
Parts List
| D391DG | band - metal band |
| D391DG-LK00 | band - link |
| D391DG-BK00 | clasp - clasp |
| D391DG-BKPP | others - spring bar for buckle/clasp |
| D391DG-LKPC | others - pipe for link |
| D391DG-LKPN | others - pin for link |
| S130BS | others - push pin |