The Seiko 8Y21-509A is a watch model based on the 8Y21 movement.
Parts List
| RE1W99JV01 | crystal |
| RE1W99JV03 | crystal |
| 35M37NA1 | crown |
| 0F220BAA3 | case back gasket - case back gasket |
| DB0055B01 | case back gasket - crown and stem gasket |
| G1447G | band |
| G1447G-BK5G | clasp - clasp |
| 2AE075L0BNG | others - minute hand |
| 3BA125F1BNG | others - second hand |
| 0351112 | others - winding stem |
| 82808990 | others - case ring |
| 8Y210250XB14 | others - dial |
| 8Y21509A | others - case back |
| 8Y21509A75 | others - case |
| 8Y2183 | others - machine code |
| A140BS | others - push pin |
| 08SC29NG | others - second hand |
| 07P37DGM | others - minute hand |
| 07P37DGH | others - hour hand |
Caliber 8Y21
