The Seiko 5S21-5A20 is a watch model based on the 5S21 movement.
Parts List
| ESCW46SJ01 | crystal |
| ESCW46SJ02 | crystal |
| 30MH0NA4 | crown |
| 0A2700N01 | case back gasket - case back gasket |
| GK19C | band - leather band |
| 10ST04DG | others - second hand |
| 0351683 | others - winding stem |
| 09TC0DAH | others - hour hand |
| 5S215A20 | others - case back |
| 5S215A2075 | others - case |
| 5S215A207N | others - case |
| 5S215A30XG14 | others - dial |
| 5S215A40XB14 | others - dial |
| 5S219 | others - machine code |
| 82822660 | others - case ring |
| A200BS | others - push pin |
| 09TC0DAM | others - minute hand |
Caliber 5S21
