The functional distinction is determinative: transmission belts transfer rotational power between shafts or pulleys, while conveyor belts move materials along a path. V-belts, flat drive belts, and ribbed belts are classified as transmission belts; wide flat belts used to carry goods on a conveyor system fall under the conveyor belt heading. When a belt could serve either function, the importer's declared end use and the product's design geometry (trapezoidal cross-section vs. flat wide profile) guide classification.

Antidumping duty orders on rubber band and belt products from China have been litigated with scope disputes over which belt types and constructions are covered. Importers should obtain a scope ruling from the US Department of Commerce if there is any ambiguity about whether their specific belt product — defined by cross-section, cord material, and application — falls within an active order's scope before committing to a China-origin supply chain.