A4 Mk3
| Exploded view of spring mat |
| 1 - | Extension spring (bottom) |
| q | Not available as separate part |
| 2 - | Extension spring (centre) |
| q | Not available as separate part |
| 3 - | Extension spring (top) |
| q | Not available as separate part |
| 4 - | Spring mat |
| q | Removing and installing → Chapter |
| q | Can be removed and installed with or without extension springs |
| 5 - | Backrest frame |