The Seiko 1M20-0A40 is a watch model based on the 1M20 movement.
Parts List
| 150A16JR02 | crystal - crystal (inorganic) |
| 8M40C0SNW1 | crown - crown |
| 0F200NA1S | case back gasket - case back gasket |
| 4648AZ | band - band |
| 4648JZ | band - metal band |
| 4648AZ-LK2 | band - link |
| 4648JZ-LK2 | band - link |
| 4648JZ-BKF | clasp - buckle |
| 4648AZ-BKL | clasp - buckle |
| 4648AZ-PB2 | clasp - parts for buckle |
| 1CH040A4BN1 | others - hour hand |
| 2CH062A2BD1 | others - minute hand |
| 81606439 | others - bracelet fixing pin |
| 81190055 | others - bracelet fixing pipe |
| 0351555 | others - winding stem |
| 82839200 | others - case ring |
| 1M200A4061 | others - case |
| 1M200A40 | others - case back |
| 1M200A70XE23 | others - dial |
| 1M201 | others - machine code |
| AD006BA12 | others - crown gasket |
Caliber 1M20
Other models with the same movement
| 1M20-0A10 |
| 1M20-0A20 |
| 1M20-0A30 |
| 1M20-0A50 |
| 1M20-0A60 |
| 1M20-0A70 |
| 1M20-5A00 |
| 1M20-5A10 |
| 1M20-5A20 |
| 1M20-5A30 |
| 1M20-5A40 |
| 1M20-5A50 |
| 1M20-5A60 |
| 1M20-5A70 |
| 1M20-5A80 |
| 1M20-5A90 |
| 1M20-5B00 |