The Seiko 4S77-0A20 is a watch model based on the 4S77 movement.
Parts List
| 260P02SN02 | crystal - crystal (sapphire) |
| 280P28SD01 | crystal |
| 280P28SB0B | crystal - crystal (sapphire) |
| 8M35E7SNW0 | crown - crown |
| 9E50A0STW1 | crown - crown |
| 0F270BAAS | case back gasket - case back gasket |
| 86580520 | crystal gasket - plastic gasket for crystal |
| A059AZ | band - band |
| 3BA035AACEL | others - small hand (6h) |
| 3DA035AABXE | others - small hand (9h) |
| 3DA035AABXR | others - sub hand |
| 3DA035AABXY | others - sub hand |
| 1FB080YHCEL | others - hour hand |
| 1FB080ZHBHS | others - hour hand |
| 2FB120YFCEL | others - minute hand |
| 2FB120ZFBHS | others - minute hand |
| 3BA045AACEL | others - small hand (6h) |
| 3BA130AACEL | others - second hand |
| 3DA045AABXE | others - small hand (9h) |
| 3DA045AABXR | others - small hand(3h) |
| 3DA045AABXY | others - small hand(3h) |
| 3DA130ABBXE | others - second hand |
| 3DA130ABBXR | others - hand |
| 3DA130ABBXY | others - second hand |
| 0351890 | others - winding stem |
| 0A0150B01 | others - crown and stem gasket |
| 81190055 | others - bracelet fixing pipe |
| 0354132 | others - winding stem |
| EB0055B01 | others - crown and stem gasket |
| 82839741 | others - case ring |
| 81612149 | others - bracelet fixing pin |
| 4S770A20 | others - case back |
| 4S770A2061 | others - case |
| 86177531 | others - crystal plastic gasket |
| 0A0150B0A | others - crown and stem gasket |
Caliber 4S77
Other models with the same movement
| 4S77-0010 |
| 4S77-0020 |
| 4S77-00A0 |
| 4S77-00B0 |
| 4S77-00C0 |
| 4S77-00D0 |
| 4S77-00E0 |
| 4S77-0A30 |
| 4S77-0A40 |
| 4S77-0A50 |