Under standard textile classification rules, fine animal hair refers to hair from certain animals (such as cashmere goats, angora rabbits, alpacas, and vicuñas) with fiber diameters generally at or below defined thresholds. The specific thresholds and species lists are set out in the tariff schedule notes. Laboratory fiber analysis from an accredited testing facility is the standard method for confirming classification, and importers should obtain test reports from their suppliers.

Certain wool blanket tariff lines have historically been subject to tariff-rate-quota (TRQ) provisions, under which a lower duty rate applies to imports within the quota quantity and a higher rate applies above it. Quota fill rates and eligibility vary by HTS line and origin. Importers should check current TRQ status with CBP and consult a customs broker to determine whether their specific product and volume qualify for within-quota treatment.