Heading 7002.10 covers solid or hollow glass balls exceeding 1 mm in diameter that have not been further worked. Glass microspheres of heading 7018 are typically hollow, very small (generally under 1 mm), and used in specialty applications such as reflective coatings, syntactic foam, and medical devices. The diameter threshold and the degree of further processing are the primary classification criteria; product technical data sheets specifying diameter and wall construction are the key supporting documents.

The 6 mm diameter breakpoint (separating 7002101000 from 7002102000) can affect both the applicable duty rate and any trade-remedy exposure, as the two lines are separately enumerated in the US tariff schedule. Importers should measure and document ball diameter accurately — typically via manufacturer's specification sheets or quality-control certificates — since misclassification between the two lines is a straightforward CBP audit target for this commodity.