Classic Accessories PolyPRO 3 Class B RV Covers. Multiple layers of protection for your home-away-from-home! The PolyPRO 3 three-ply fabric top keeps out rain and snow, keeping your prized beauty protected in the off-season. The sides are rugged PolyPRO 1 fabric that guards against mud, dirt, nicks and scratches. A built-in air vent system reduces wind stress and interior moisture. Triple-ply PolyPRO 3 top fabric keeps out rain and snow Single-ply PolyPRO 1 sides reduce wind stress and inside moisture Adjustable front and rear tension panels and elasticized hem corners provide a custom fit Integrated rope attachment system and included bag helps reduce crawling under the RV Zippered panels allow access to RV doors and engine area Backed by a 3-yr. limited manufacturer's warranty. Model 1: Fits Class B RVs up to 20'l., 117"h. max. Model 2: Fits Class B RVs up to 20-23'l., 117"h. max. Model 3: Fits Class B RVs 23-25'l., 117"h. max. Model 4: Fits Class B RVs 25-27'l., 117"h. max. State Model, as available in the Shopping Cart.