Mercedes-Benz 2004 C-Class Wagon Operator's Manual page 206

Controls in detail
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5 Button
Open tailgate.
Press button 5.
The flap opens downward.
206
From cargo compartment, slide skis
into ski sack.
Warning!
The ski sack is designed for up to four pairs
of skis. Do not load the ski sack with other
objects.
Always fasten the ski sack securely. In an
accident, an unfastened ski sack can cause
injury to vehicle occupants.
6 Strap
Tighten strap 6 by pulling at the loose
end (arrow) until the skis in the ski sack
G
are tightly secured.