In the case of an original metal sliding roof, there are seals at the top that ensure the roof is watertight and protect it from the wind.
There are two seals, the most visible one is on the edge of the body and a foam rubber seal on the back of the roof.
Many people don't know about the foam rubber gasket on the back, it is often so abused that it seems like it was never there. This foam rubber seal can only be seen when the sliding roof is removed from the car, it must be glued to the end of the roof.
All Volkswagen Beetles with metal sliding roofs have this foam rubber that serves as a good windproofing.
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