The Seiko Y121-8A40 is a watch model based on the Y121 movement.
Parts List
| 310T56ARG2 | crystal - crystal |
| 310T56ARS2 | crystal - crystal |
| 8M40C5SNG2 | crown - crown |
| 8M40C5SNS0 | crown - crown |
| 0F260BA1S | case back gasket - case back gasket |
| FFE2JZ | band - band |
| FFE4JZ | band - band |
| FFE3KZ | band - band |
| FFE5KZ | band - band |
| 1AE080L0BNG | others - hour hand |
| 1AE080L0BNS | others - hour hand |
| 2AE120L0BNG | others - minute hand |
| 2AE120L0BNS | others - minute hand |
| 3BA125F1BNG | others - second hand |
| 3BA125F1BNS | others - second hand |
| AC006BAD1 | others - crown and stem gasket |
| 0354786 | others - winding stem |
| Y1218A4002 | others - case |
| Y1218A4001 | others - case |
| 82729300 | others - case ring |
| S180BS | others - push pin |