Vulcanized fiber, polyester film, foam, and nonwoven synthetic substrates are the most common backings classified here. Nonwoven abrasive pads (such as those used for surface conditioning) are a notable example — they are neither woven textiles nor paper, placing them squarely in the NES category. Importers should obtain material composition documentation from the manufacturer to support classification decisions.

Composite backings — for example, a paper layer laminated to a polyester film — require classification based on the essential character of the backing as a whole. Customs authorities may look at which layer provides the primary structural function. Consulting a licensed customs broker and requesting a binding ruling from CBP is advisable when the backing construction is ambiguous.