I installed rear speakers in my xf coupe and while the installer had the left rear panel inside the trunk out I noticed down at almost the bottom of the rear fender was a 4x4 inch plastic square black louver thing attached. I reached down and the louvers would open and close, does anyone know what this thing is or does?

Tom

 

when you shut the doors it releases the pressure so your ears don't take it in instead ... if it is what i think you are talking about ... louvers that open to the exterior ...

 

thank you for the reply.
the odd thing is that there is nothing attached to it.

 

the vent exit is on the underside/bottom side of the rear tail lights.

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