See also:

Mercedes-Benz M-Class Owners Manual
...

Adjusting the active multicontour seat
You can adjust the active multicontour seat using COMAND. If PRE-SAFE® has been activated, the air pressure in the air chambers (the side bolsters of the seat cushion and backrest) of the mu ...

Emergency Tensioning Devices, belt force limiters
The front seat belts and the outer seat belts in the rear are equipped with ETDs and seat belt force limiters. The ETDs tighten the seat belts in an accident, pulling them close against the body. ...