Handles or straps that passengers can hold on to while driving, or that serve as an aid for getting in and out of the car, are never mounted directly to the body. If you were to hold onto the straps, a lot of force would be applied, so the trap mounting location is reinforced with a mounting bracket.
Underneath this mounting bracket is a plastic underlay, which prevents damage to the body and/or headliner.
Note: If belt hooks are present, this underlay is not necessary, the belt hook also acts as an underlay.
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