When a yarn contains both wool and fine animal hair, classification follows the predominant fiber by weight. If fine animal hair (cashmere, alpaca, mohair, etc.) predominates, the yarn falls under 5108; if wool predominates, it goes to 5106 or 5107 depending on the spinning system. For blends where neither clearly predominates, the chapter notes and GRI 3 apply to determine the essential character.

The US tariff schedule assigns separate lines to carded (510810) and combed (510820) fine animal hair yarn, and duty rates may differ between them. Importers should verify the applicable rate for each subheading and confirm the spinning method with the supplier, as the distinction is also relevant to end-use specifications for luxury textile mills.