Classification in this residual heading is appropriate only after systematically ruling out more specific headings for the material in question. The General Rules of Interpretation require that goods be classified in the most specific applicable heading. A CBP binding ruling is the most reliable way to confirm classification for unusual or novel animal-derived materials, and a licensed customs broker can assist with the analysis.

The applicable agency depends on the nature of the specific material. USDA APHIS may be involved if the product poses an animal-disease risk; FDA may have jurisdiction if the material is intended for food, drug, or cosmetic use; and US Fish & Wildlife Service is relevant if any CITES-listed species is involved. Because this heading covers a wide range of materials, importers should identify the specific substance and its intended use to determine which agencies require notification or permits.