Comfort World 4000 Reinforced Vinyl Siding provides what you want in a siding-superior panel design, incredible curb appeal and a wide choice of design options. Designed for performance the Comfort World 4000 Siding is engineered and manufactured to provide not just beauty, but performance. A combination of a rolled-over nail hem and specially designed locking system provide superior wall attachment strength. In fact, our siding has been independently tested to withstand catagory 5, hurricane-force winds. This design also provides another, perhaps more important attribute, superior rigidity, helping to ensure straight course lines and even walls on both new and existing homes.