Those camping world and wal mart vent caps are all plumbing vent caps. They are used for venting the gray & black tanks. These are attic vents. A totally different vent and cap. They are not interchangeable. Some call them mushroom attic vent caps. Its just for some reason you have to buy the whole assembly that is installed thru the rubber roof, screwed into the roof & has roof sealant or goop around it like everything on the roof. The top or cap is the only thing you would ever need as it covers the base, unless you would hit something and rip out the base. The tops become brittle and crack and break from the sun and are very thin plastic to start with......