RV PolyPRO™ 3 Class A Cover XT 37-40 ft. This cover is specially designed for extra tall Class A RVs and has zippered panels to allow access to all four sides. Triple-ply Polypro 3 keeps out rain and snow from the top of the cover, and single-ply sides protect against rain, snow, dirt, nicks, and scratches for all-season protection. An integrated air vent system combined with quick drying Polypro 1 sides reduce wind stress and vent inside moisture. Create a custom fit with the adjustable front and rear tension panels and elasticized hem corners. The integrated rope attachment system and a provided toss bag helps to reduce crawling under the RV for installation. Neat zippered panels give you access to the RV doors and engine areas without having to remove the cover itself.