CBP generally applies the GRI principle of essential character and the specific exclusion notes. Filters that are clearly designed and marketed as replacement parts for a specific vacuum cleaner model tend to classify under 8508.70 as parts. Generic filter media or filter housings sold for broad industrial filtration use are more likely to fall under 8421. The product's design specificity and how it is presented commercially are the key factors.

Each component must be classified individually based on its own description and function. Parts exclusively identifiable as vacuum cleaner components go under 8508.70, while parts for other electromechanical domestic appliances fall under 8509.90 or another applicable heading. Mixed shipments should be itemized on the commercial invoice by part number and function to support accurate classification and avoid CBP examination delays.