8539.10.00 - Sealed beam lamp units

HTS Code 8539.10.00 specifically classifies "Sealed beam lamp units." These are self-contained lighting devices designed with a sealed glass envelope that encloses the filament, reflector, and lens. The entire unit is manufactured as a single, integrated component, commonly found in automotive headlights and older aircraft lighting systems. Unlike other filament lamps, the sealed nature of these units prevents contamination of the filament and ensures a consistent beam pattern throughout their operational life.

This category is distinguished from other HTS 8539 subheadings by its sealed construction. For example, while sibling categories cover other types of filament lamps, discharge lamps, UV/IR lamps, and LED light sources, 8539.10.00 is exclusively for those where the bulb, filament, reflector, and lens are integrated and sealed within a single unit. It also differs from parts of lamps (8539.90.00) as it represents a complete, functional lamp unit rather than individual components.

Within the classification of sealed beam lamp units, further subdivisions are made based on physical dimensions. The subcategories delineate between units measuring under 15.24 cm and those measuring 15.24 cm or over. This dimensional distinction is a key classification criterion, likely reflecting different applications and specifications for these self-contained lighting assemblies.