The Seiko 4N21-0720 is a watch model based on the 4N21 movement.
Parts List
| 190A02LN03 | crystal - crystal |
| 6M30A1NNG1 | crown - crown |
| 0F170BAA1 | case back gasket |
| AC004BAA1 | case back gasket - crown and stem gasket |
| 86170210 | bezel gasket |
| ZA79B | band - band |
| 1BF050A1BNG | others - hour hand |
| 2BF075A1BNG | others - minute hand |
| 3BA075F1BNG | others - second hand |
| 0351155 | others - winding stem |
| 82833515 | others - case ring |
| 4N2107206YA | others - case |
| 82344035 | others - bezel |
| 4N210720 | others - case back |
| 4N211390XS19 | others - dial |
| 4N2164 | others - machine code |
| T070BS | others - push pin |