. . . "For example, structural foam polypropylene molded using a low pressure process is the preferred method and material for making the header and frame, but other materials can be used, including other structural foam polymer materials, other thermoplastic resins such as polypropylene, polyethylene, high density polyethylene, acrylonitrile butadiene styrene (???ABS???), acetal, polyurethane, nylon, an" .