Yet another thing for me to find out, I have never had one but my neighbour bought one from Boatworld, price about £70 its gigantic and covers the whole caravan including the hitch. At the time he ordered for a 21 ft. Two years on and apart from a tear from his front top rail it still looks good . The material is strange its not plastic but feels cotton like .Anyway looking on the web some people say it should be white underneath to stop staining other type covers are one colour and you pay for what you get, so it seems covers are not 100% waterproof is that because it breaths?. Any comments on what you have would be appreciated.Thanks.