The Seiko 1E20-639B is a watch model based on the 1E20 movement.
Parts List
| ES0A18SV0E | crystal |
| 25M36NA5 | crown |
| 0E140NA1S | case back gasket - case back gasket |
| B5715 | band - metal band |
| 81181859 | others - bracelet fixing pipe |
| 81606479 | others - bracelet fixing pin |
| 1E202390XL14 | others - dial |
| 1E20639B | others - case back |
| 1E20639B25 | others - case |
| 1E208 | others - machine code |
| 82833560 | others - case ring |
| 0351931 | others - winding stem |
| DZ0041B01 | others - crown and stem gasket |
| 04V02DGM | others - minute hand |
| 04V02DGH | others - hour hand |
Caliber 1E20
