5603.94.10.90 - Other

This HTS subheading, 5603.94.10.90, specifically classifies "Other" nonwoven floor covering underlays that weigh more than 150 g/m². These are specialized textile materials, not woven or knitted, designed to be placed beneath carpets, rugs, or other floor coverings to provide cushioning, insulation, or protection. They are produced by bonding or interlocking fibers, often through mechanical, thermal, or chemical means, and are distinct from finished floor coverings themselves.

The key differentiator for this classification is its specific focus on floor covering underlays when they are not made of wool or fine animal hair, which is covered under the sibling category 5603.94.10.10. Therefore, this subheading would encompass underlays made from a wide range of synthetic or other animal fibers not considered "fine animal hair," such as polyester, polypropylene, or cotton. The weight criterion of over 150 g/m² ensures that lighter weight nonwovens, or those used for different purposes, are excluded.

As a leaf node, this classification does not have further subdivisions. Classification into 5603.94.10.90 is determined by the material composition (excluding wool and fine animal hair) and its specific end-use as a floor covering underlay, provided it meets the weight threshold.