Most Caravans or campers have a PVC tube, or two. You know the type for poles, annex bars, fishing rods etc. The screw caps often get gummed up and are hard to remove. Get a "U" shaped drawer handle and screw it to the cap. Makes removing the cap a lot easier. You will have to shorten the screws first. Get a nut that fits the screw, tighten nut, cut the screw to length and remove the nut. This will help repair the thread after you have cut it. Happy caravaning.