Customs tariff amendments replace scheduled rate entries across HS chapters, adjusting ad valorem and unit-based duties. Amends the First Schedule to the Customs Tariff Act by substituting specified entries in column (4) and, where indicated, column (5) for listed chapters and sub-headings. The Schedule prescribes uniform ad valorem percentages for many chapters, identifies chapter-specific exceptions with alternative percentages, provides paired column substitutions including percentage less per-unit adjustments or reduced column(5) rates, inserts a few per-unit supplements for specific sub-headings, and omits NOTE 2 in Chapter 89.