The Seiko 4S77-0020 is a watch model based on the 4S77 movement.
Parts List
| 290P02SN02 | crystal - crystal (sapphire) |
| 9M50B1SNW0 | crown - crown |
| 8M35E7SNW0 | crown - crown |
| 9M50F5SNS0 | crown - crown (3h) |
| 0F300NAA1 | case back gasket - case back gasket |
| DB0055B01 | case back gasket - crown and stem gasket |
| 86591936 | crystal gasket - plastic gasket for crystal |
| A052AB | band - band |
| A052DB | band - band |
| 1FB080ZHBHJ | others - hour hand |
| 2FB120ZFBHJ | others - minute hand |
| 3DA045AABHJ | others - small hand (9h) |
| 3DA130ABBHJ | others - second hand |
| 1FB080ZHBHS | others - hour hand |
| 2FB120ZFBHS | others - minute hand |
| 3DA045AABHS | others - small hand (9h) |
| 3DA130ABBHS | others - second hand |
| 3DA035AABHS | others - small hand (6h) |
| 3DA035AABHJ | others - small hand (6h) |
| A170BS | others - push pin |
| 4S77002061A | others - case |
| 89923379 | others - casing spring |
| 82837431 | others - case ring |
| 4S770020 | others - case back |
| 4S7700209TA | others - case |
| 270P02SN02 | others - crystal (sapphire) |
| 86592536 | others - crystal plastic gasket |
| EB0055B01 | others - crown and stem gasket |
| 0351890 | others - winding stem |
Caliber 4S77
Other models with the same movement
| 4S77-0010 |
| 4S77-00A0 |
| 4S77-00B0 |
| 4S77-00C0 |
| 4S77-00D0 |
| 4S77-00E0 |
| 4S77-0A20 |
| 4S77-0A30 |
| 4S77-0A40 |
| 4S77-0A50 |