a composite high density plastic sheet , comprising a thermoplastic elastomer filled in substantial amount with an inorganic material , and intimately blended with a high strength low density polyethylene whereby to provide in one product the benefits of sound attenuation as well as inhibiting water and dust entry . the sheet can be cold - formed to include a pocket portion for use in applications such as receiving vehicle apparatus . provision of a separate layer of the low density polyethylene assists in the sheets being stacked and adhesive permits the sheet to be removably attached to a surface of the apparatus .