5402.45 - Other, of nylon or other polyamides:

This HTS category, 5402.45, encompasses other synthetic filament yarns, specifically those of nylon or other polyamides, that are not sewing thread and are not put up for retail sale. These yarns are characterized by being single, untwisted, or having a twist not exceeding 50 turns per meter. This broad classification applies to nylon or polyamide filament yarns that do not fall under more specific subheadings within heading 5402.

It is important to distinguish this category from its siblings. For instance, 5402.44.00 specifically covers elastomeric yarns, while 5402.46.00.00 and 5402.47 relate to polyester yarns, either partially oriented or otherwise. Similarly, 5402.48.00 is designated for polypropylene yarns, and 5402.49.00 covers "other" yarns not otherwise specified within this broader group. Therefore, 5402.45 acts as a catch-all for non-elastomeric, non-polyester, and non-polypropylene synthetic filament yarns of nylon or polyamides.

Within 5402.45, two subcategories exist to further refine the classification. 5402.45.10.00 is for specific colored multifilament yarns meeting precise decitex and twist criteria, intended for the manufacture of doll wigs, indicating a highly specialized application. The remaining yarns of nylon or other polyamides not meeting these specific criteria are classified under 5402.45.90, which serves as the residual category for other types of nylon or polyamide filament yarns within this heading.