The ADCO 34812 Class C Designer Series Tyvek Plus Wind RV Cover is made to fit a 20' 1" to 23' size. This gray and white cover has a triple-layered Tyvek top panel with triple layered polypropylene sides. It provides protection for all climates, including UV and wind resistance. The slip seam strap system fits the RV's shape to reduce the amount of wind impact, while the built-in vents allow for air to pass through.