The Seiko 5S21-0A10 is a watch model based on the 5S21 movement.
Parts List
| 340W22HK01 | crystal |
| 340W22HK | crystal |
| 35M82NA1 | crown - crown |
| 15T04NBM | crown |
| 0A3100N01 | case back gasket |
| 0A3100N0 | case back gasket |
| 86580960 | crystal gasket |
| ZNJ15G | band |
| ZNJ16G | band |
| ZNJ17G | band |
| 0351683 | others - winding stem |
| 82811000 | others - case ring |
| 5S210A10 | others - case back |
| 5S210A1075 | others - case |
| 5S210A10XS19 | others - dial |
| 5S210A20X919 | others - dial |
| 5S210A20XS19 | others - dial |
| 5S218 | others - machine code |
| A160BS | others - push pin |
| 0Z0060B01 | others - crown and stem gasket |
| 15SC02TB | others |
| 15T04NBH | others |
Caliber 5S21
