The Finnish Transport and Communications Agency Traficom has published a YouTube video about mandatory equipment for vehicles used in instruction under a driving instruction permit. Markus Vanhala from Ajovarma shows the equipment and their most common problems on a video. Watch the video (in Finnish):
Opetus ja tutkintoajoneuvon vaatimukset (YouTube)

You can read more about driving instruction permit on Traficom’s -pages:
Driving instruction permit (Traficom)