2933.21Subheading
Heterocyclic compounds; with nitrogen hetero-atom(s) only, containing an unfused imidazole ring (whether or not hydrogenated) in the structure, hydantoin and its derivatives
Section VI — Products of the chemical or allied industries
This is a 6-digit subheading — the most specific level of the international HS. Country tariff schedules extend it further; the US tariff lines (HTS) below refine it to 8–10 digits for duty purposes.
US tariff lines for this subheading are not in the bundled starter dataset yet — the full HTS schedule is coming soon. You can still search by code in the tariff simulator.