Ivory and tortoise-shell from CITES-listed species require both an export permit from the country of origin and a US Fish & Wildlife Service import permit. Antique ivory may qualify for an exemption but requires documentation of age and provenance. Importers should verify species-level CITES appendix status before shipment, as controls differ by species.

Heading 0504 covers guts, bladders, and stomachs of animals other than fish, whether or not split, in their raw or simply cleaned state. Casings that have been further processed — salted, dried, or otherwise prepared for direct use — may remain in 0504 if they are still in a natural state, but manufactured or artificial casings move to other chapters. The degree of processing and whether the product retains its natural character are the key classification criteria.