A bend is the dorsal (back) section of a split hide, characterized by tight, dense fiber structure that produces firm, durable leather — preferred for sole leather, belting, and heavy goods. A belly is the ventral section, which has a looser, more irregular fiber structure and is typically used for lower-grade or softer leather applications. Tanners specify which section they require, and pricing reflects the quality differential.

If a hide section meets the weight and species criteria of a more specific SITC heading — for example, falling within the light-weight whole-skin thresholds of 21121 — it should be classified there rather than under the residual NES provision. Accurate measurement and species documentation at export help prevent reclassification disputes at the US port of entry.