Viper CS Crawl Space Class A Woven Reinforced Vapor Barrier - 12 ft x 100 ft x 16 milsViper CS Crawl Space Class A Woven Reinforced Vapor Barrier is a high performance crawl space vapor barrier designed to prevent moisture migration from the soil into the crawl space. It helps guard against mold, mildew, allergens, fungus, radon gas, methane gas, heat loss due to damp insulation, wood rot and overall degradation of the crawl space. It is manufactured using woven high density fibers yielding the highest strength to weight ratio, tensile