Some plastics that are used in the production of gaskets include nylon, polyvinyl chloride (PVC), silicone, polytetrafluoroethylene (PTFE), polyurethane (PU), polyacrylate, and various thermoplastic elastomers (TPEs). Gaskets made of plastics are described in subheading 3926.90. The Section XVII Note 2(a) exclusion for joints, washers or the like precludes gaskets of any material from classification in any of the provisions of that Section. Therefore, plastic gaskets for use in the goods of Section XVII (i.e. motor vehicles, transportation vehicles etc.) would be classifiable in subheading 3926.90 rather than elsewhere in the tariff. Plastic gaskets that are parts of articles provided for in Chapters 84, 85 or 90 are classifiable as parts of the articles in those Chapters, assuming they are specially designed for use solely or principally with those articles. For instance classification of plastic gaskets specially made for use with a filtering system for water and wastewater is classified in subheading 8421.99 as parts of filtering machinery of heading 8421.