Stabilizer heads and poles sit at the sides or underside of the car. When it touches the wall or edge of the track, they help it stay level instead of riding up or catching.
For how each kind of part is used and tuned, see Tamiya Hong Kong's Mini 4WD setting guide (in Chinese).
10 parts
Product pictures are thumbnails of TAMIYA's official photos and remain TAMIYA's copyright. This is an unofficial fan site with no affiliation to TAMIYA.