RV PolyPRO™ 3 Travel Trailer Cover 20-22 ft. Thick, triply-ply Polypro 3 makes up the top of this cover, and single-ply covers the sides to protect against rain, snow, dirt, nicks, and scratches for all-season protection. An integrated air vent system combined with quick drying Polypro sides reduce wind stress and vent inside moisture. Create a custom fit for your travel trailer with the adjustable front and rear tension panels and elasticized hem corners. With an integrated rope attachment system and a provided toss bag, you can reduce the need to crawl under the RV during installation. Its zippered panels allow access to the RV doors and engine areas so you don't have to fuss with taking the entire cover off to get inside the trailer.