4418.21 - Of tropical wood:

This HTS category, 4418.21, specifically covers doors, their frames, and thresholds that are constructed from tropical wood. The defining characteristic for classification under this heading is the origin of the wood used in their manufacture. Tropical wood, as defined by international conventions and customs authorities, generally refers to timber sourced from specific geographical regions, often characterized by hardwood species. These goods are integral to building construction and renovation projects, serving the primary function of access and closure for spaces within a structure.

This category is distinguished from its sibling, 4418.29 ("Other"), by the explicit requirement for the wood material to be of tropical origin. While 4418.29 would encompass doors, frames, and thresholds made from non-tropical woods (such as pine, oak, or maple), 4418.21 narrows the scope to those specifically using timber from tropical forests. This distinction is crucial for compliance with trade regulations and potential tariff implications associated with the sourcing of the wood.

Within 4418.21, further subdivisions exist to provide more granular classification. The subcategory 4418.21.40.00 is designated for "French doors," a specific style characterized by multiple glass panes extending for most of the door's length. The remaining doors, frames, and thresholds falling under this tropical wood category are classified under 4418.21.80, "Other." This hierarchical structure allows for precise identification based on both material origin and specific product type.