Technical drawings, product specifications, and commercial invoices that clearly identify the component type—such as 'temple arms,' 'hinges,' or 'nose pads'—are the most effective documentation. If the items are presented in bulk packaging typical of manufacturing inputs rather than retail-ready pairs, that also supports a parts classification. Customs may request samples or additional technical evidence if the distinction is not clear from the paperwork.

Not necessarily. Trade-remedy measures such as antidumping or countervailing duties are applied at the HTS tariff line level, and the lines covering frame parts may differ from those covering complete frames. Importers should check the specific HTS classification of their parts against any active orders or Section 301 lists, as coverage can vary by component type and country of origin.