The Seiko 5S21-0A21 is a watch model based on the 5S21 movement.
Parts List
| 310W74JN01 | crystal - crystal |
| 45M86EH1 | crown |
| 0A3100N01 | case back gasket |
| AC06A | band - band |
| 13T04DBM | hand - minute hand |
| 13SC20TB | others - second hand |
| 82811000 | others - case ring |
| 0351684 | others - winding stem |
| 5S210A21 | others - case back |
| 5S210A21RN | others - case |
| 5S210A31XS19 | others - dial |
| 5S218 | others - machine code |
| 81350820 | others - spring |
| 81871343 | others - case bow |
| 87020380 | others - back plate |
| 13T04DBH | others - hour hand |
| 0Z0060B01 | others - crown and stem gasket |
Caliber 5S21
