Polyethylene Underbelly is a stout cloth material that has been used in the manufacture of mobile homes for decades. Since the 1980's OEMs have used this black cross-hatched fabric, reminiscent of the same material you would find in a tarp (standard use, not construction grade) this cloth is utilized in the protection of mobile homes, trailers, sheds, RVs, homes, and other residential applications. It's flexible, easy to install, tear-resistant, and is water repellant so that you will see little to no water encroachment in your vehicle. Flex-Mend is a front-of-industry mending tape that not only matches the texture and looks of bottom under-fabrics but is a permanent fixture once correctly applied. The specially-engineered adhesive applies easily, and the woven poly-film will become a seamless part of the original fabric.