5509.91.00.00 - Mixed mainly or solely with wool or fine animal hair (607)

This HTS classification, 5509.91.00.00, specifically covers yarns, other than sewing thread, made from synthetic staple fibers. These yarns are not intended for retail sale and are characterized by being mixed mainly or solely with wool or fine animal hair. This composition means that the dominant fiber or a substantial portion of the blend consists of wool or other animal hairs such as cashmere, mohair, or alpaca, alongside the synthetic staple fibers.

It is important to distinguish this category from its siblings. HTS 5509.92.00.00 addresses similar synthetic staple fiber yarns that are mixed mainly or solely with cotton, highlighting the primary non-synthetic fiber in the blend as the differentiating factor. Category 5509.99 pertains to "Other" yarns within this group, which would encompass blends not primarily composed of wool/fine animal hair or cotton, or other combinations not otherwise specified.

As this is a leaf node within the HTS structure, there are no further subcategories. Classification into 5509.91.00.00 is therefore determined by the material composition: the yarn must be of synthetic staple fibers and predominantly or exclusively blended with wool or fine animal hair, and not put up for retail sale. Examples include spun yarns of polyester or nylon blended with merino wool, or acrylic staple fibers blended with alpaca fibers, when presented in bulk for further manufacturing and not packaged for consumer purchase.