NECK-PRO head restraints
The NECK-PRO head restraints increase protection to the driver's and front passenger's head and neck. To this end, the NECK-PRO head restraints on the driver's and front-passenger seats are moved forwards and upwards in the event of a rear-end collision of a certain severity. This provides better head support.
WARNING 
Do not secure any objects (e.g. coat hangers)
on the NECK-PRO head restraints. Otherwise,
the NECK-PRO head restraints may not
function properly, or in the event of a rear-end
collision may not be able offer the level of
protection they are designed to provide.
If the NECK-PRO head restraints have been triggered in an accident, reset the NECK-PRO head restraints on the driver’s and frontpassenger seat. Otherwise, the additional protection will not be available in the event of another rear-end collision. You can recognize when NECK-PRO head restraints have been triggered by the fact that they have moved forwards and can no longer be adjusted.
See also:
Snow chains
For safety reasons, Mercedes-Benz
recommends that you only use snow chains
which have been specially approved for your
vehicle by Mercedes-Benz, or are of a
corresponding standard of quality.
...
Useful information
This Operator's Manual describes all models and all standard and optional equipment
of your vehicle available at the time of publication of the Operator's Manual. Country-specific
diffe ...
Seat belt adjustment
The seat-belt adjustment function adjusts the
driver's and front-passenger seat belt to the
upper body of the occupants.
The belt strap is tightened slightly when:
• you engage the belt tongue i ...