The Seiko 1M20-5A90 is a watch model based on the 1M20 movement.
Parts List
| RE3A10JR02 | crystal - crystal |
| 8Z50A2STWA | crown - crown |
| 8Z50A2STWB | crown - crown |
| 0H019BAD2 | case back gasket - crown and stem gasket |
| 0F210NA1S | case back gasket - case back gasket |
| 46951B | band - band |
| 4H541B | band - band |
| 1CG042S0BDS | others - hour hand |
| 2CG057S0BDS | others - minute hand |
| 82839600 | others - case ring |
| 81612029 | others - bracelet fixing pin |
| 0351555 | others - winding stem |
| 1M205A9061 | others - case |
| 1M205A90 | others - case back |
| 1M205A9061A | others - case |
| 81504289 | others - case back screw |
| 1M200B10XB13 | others - dial |
| 1M200B10XG13 | others - dial |
| 1M201 | others - machine code |
| 81504269 | others - screw |
Caliber 1M20
Other models with the same movement
| 1M20-0A10 |
| 1M20-0A20 |
| 1M20-0A30 |
| 1M20-0A40 |
| 1M20-0A50 |
| 1M20-0A60 |
| 1M20-0A70 |
| 1M20-5A00 |
| 1M20-5A10 |
| 1M20-5A20 |
| 1M20-5A30 |
| 1M20-5A40 |
| 1M20-5A50 |
| 1M20-5A60 |
| 1M20-5A70 |
| 1M20-5A80 |
| 1M20-5B00 |