HyperVent is a material that eliminates condensation, water, mildew, and other moisture problems on boats. HyperVent is a special material comprised of a white spun polymer woven into a large, open, 3/4'' thick configuration that is bonded to a breathable white fabric layer. Stiff yet flexible, the texture of HyperVent is not felt through the thinnest mattress. The semi-rigid structure that elevates the mattress and bedding 3/4'' (even with a heavy person) and allows nearly unobstructed air flow. Easy to cut (scissors work fine) and virtually maintenance free. (Sold by foot)