5402.51.00.00 - Of nylon or other polyamides (606)

This HTS category, 5402.51.00.00, specifically classifies synthetic filament yarn, excluding sewing thread and monofilament under 67 decitex, that is not packaged for retail sale. The defining characteristic of this subcategory is that it encompasses single yarns exhibiting a twist exceeding 50 turns per meter, and crucially, these yarns are composed of nylon or other polyamides. This focus on material composition is key to its differentiation within the broader "Other yarn, single, with a twist exceeding 50 turns/m" group.

Distinguishing this category from its siblings, 5402.52 covers polyester yarns, while 5402.53.00.00 is reserved for polypropylene yarns. Furthermore, the residual category 5402.59.01.00 captures other synthetic filament yarns that do not fall under the specific classifications of nylon, polyester, or polypropylene. Therefore, the primary distinguishing factor for 5402.51.00.00 is its exclusive focus on the polyamide family of synthetic fibers.

As this is a leaf node within the HTS structure, there are no further subcategories to introduce. Classification within this code hinges on confirming the material is indeed nylon or another polyamide, that it is a single filament yarn (not plied), possesses a twist exceeding 50 turns per meter, and is not presented for direct consumer purchase.