7604.21.00.90 - Other

This HTS classification, 7604.21.00.90, specifically covers hollow profiles made of aluminum alloys that do not fall under the more specific subcategory. Hollow profiles are characterized by their tubular or cored cross-sections, meaning they have an empty space running through their length. This category encompasses a wide array of extruded aluminum shapes designed for various industrial and construction applications where lightness, strength, and corrosion resistance are paramount. Examples include hollow structural sections, window and door frames, and various tubing used in manufacturing and engineering.

This category is distinguished from its sibling, 7604.21.00.10, which specifically enumerates heat-treatable industrial alloys as defined in statistical note 7 of Chapter 76. Therefore, 7604.21.00.90 is for hollow aluminum alloy profiles made from alloys that are *not* heat-treatable or do not meet the criteria outlined in that specific statistical note. The classification hinges on the metallurgical properties of the aluminum alloy used in the extrusion process.

As this is a leaf node in the HTS classification system, there are no further subcategories under 7604.21.00.90. All qualifying hollow aluminum alloy profiles that do not fit the more narrowly defined sibling category are captured here. The definitive factor for classification under this code is the absence of the specific heat-treatable characteristics mandated for the adjacent category, coupled with the hollow profile form factor of the aluminum alloy product.