Abstract: A roof rail retainer with an adapter component, has a fastening apparatus for mounting on a roof of a vehicle and a fastening device for mounting a roof rail of the vehicle. The fastening apparatus has a bolt element which is preferably provided with a thread and is surrounded by a compressible sealing ring. At least one supporting element is associated with the bolt element and on the one hand lies in contact with the adapter component or is connected to the adapter component, and on the other hand has at least one supporting surface which can be placed onto the roof of the vehicle. A thickness of the uncompressed sealing ring as viewed in an axial direction of the bolt element is greater than the supporting length of the supporting element.