The Seiko 2C21-5100 is a watch model based on the 2C21 movement.
Parts List
| ESMN95JN00 | crystal - crystal |
| 32N19NS1 | crown |
| 32N19NA1 | crown |
| 0H1750B01 | case back gasket |
| DH0100B01 | case back gasket - crown and stem gasket (4h) |
| WS04A | band - band |
| WS05A | band - band |
| 08S15D2H | others - hour hand |
| 08S15D2M | others - minute hand |
| 08S15DHH | others - hour hand |
| 08S15DHM | others - minute hand |
| 08SS03NS | others - second hand |
| 08SS03NG | others - second hand |
| 0351225 | others - winding stem |
| 2C21510025 | others - case |
| 82706550 | others - case ring |
| 2C2151002E | others - case |
| 2C210280XG14 | others - dial |
| 2C210280XS13 | others - dial |
| 2C2110 | others - machine code |
| T080AS | others - push pin |
Caliber 2C21
