Mills specify combed (worsted) yarn by metric count (Nm), twist per meter, and surface smoothness — properties that reflect the parallel fiber alignment achieved by combing. Carded yarn is typically specified by bulk, loft, and hairiness. For import classification purposes, the processing method (carded vs. combed) must be declared accurately, as it determines the applicable heading even when fiber content percentages are identical.

Yes, mixed shipments are common. Each yarn type must be declared and entered under its correct heading based on its individual fiber content — they cannot be averaged or combined into a single line. Importers should ensure commercial invoices and packing lists itemize each yarn grade separately by fiber content percentage to facilitate accurate CBP entry and avoid post-entry audit issues.