Classification follows the constituent material that imparts the essential character. Predominantly synthetic-fiber lashes fall under 670419, while predominantly human-hair lashes fall under 670420. When the blend is ambiguous, CBP's essential-character analysis or a binding ruling is the appropriate path.

Medical end-use does not by itself change the tariff classification or duty rate — the article is still classified by its material and construction under 6704. However, certain duty-suspension or humanitarian-import provisions may apply in specific circumstances; a licensed customs broker can advise on whether any applicable provision covers a particular shipment.