Heading 7020 covers glass articles that do not fit more specific headings — examples include glass envelopes for vacuum tubes, glass inners for vacuum flasks, glass beads not for jewelry, and certain technical glass components. The key step is ruling out all more specific headings in the glass chapters before defaulting to 7020.

Work through the glass chapter systematically: flat glass, cast glass, containers, tableware, glass fibers, and mirrors each have dedicated headings. Only after confirming none of those headings captures the article should 7020 be used. A binding ruling from CBP is advisable for novel or borderline glass products.