PolyPRO (tm) 3 Folding Camper Covers, fits 18' - 20' L. Triple-ply PolyPRO (tm) 3 top with breathable single-ply PolyPRO (tm) 1 sides Protects against rain, snow, dirt, nicks and scratches for all-season protection. Integrated Rope System Includes a weighted toss bag making installation easy and helps reduce crawling under your RV. Front and Rear Tension Panels and Elasticized hem corners Provide a more custom fit. Air Vent System Reduces wind stress and inside moisture. Sophisticated Zipper System Long zipper pulls allow access to any part of the RV even when covered. PolyPRO (tm) 3 covers include Storage bag, ladder cap and tie-down rope. Warranty 3 year hassle-free warranty.