Gaskets and joints under 8484 are characterized by metal sheet as a component — either as the primary material or combined with rubber, cork, or other materials. A purely rubber O-ring or seal with no metal-sheet element typically classifies under the rubber-articles chapter. The presence and structural role of the metal layer is the deciding factor.

Sets or assortments of gaskets and similar joints packaged together for retail sale or as repair kits are specifically provided for under 848490, so the set is classified as a whole rather than broken down by individual component. If the assortment contains items that are not gaskets or similar joints, the general rules for mixtures and sets in the GRI apply.