The Seiko 4N21-0100 is a watch model based on the 4N21 movement.
Parts List
| 175A02SN01 | crystal |
| 175W21SN01 | crystal |
| 32M63NA1 | crown |
| 0F140BAA3 | case back gasket - case back gasket |
| ZA23A | band - metal band |
| 3BA075F1BNG | others - second hand |
| 1BH047A1BNG | others - hour hand |
| 2BH070A1BNG | others - minute hand |
| 07SC43NG | others - second hand |
| 07T49NGM | others - minute hand |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |
| 81181459 | others - bracelet fixing pipe |
| 81604259 | others - bracelet fixing pin |
| 81606899 | others - bracelet fixing pin |
| 82841030 | others - case ring |
| 4N210100 | others - case back |
| 4N21010075 | others - case |
| 4N210160XS19 | others - dial |
| 4N2164 | others - machine code |
| 07T49NGH | others - hour hand |