For coiled products, the subheadings break at 3 mm or more (720915), over 1 mm to under 3 mm (720916), 0.5 mm to 1 mm (720917), and under 0.5 mm (720918). The same four thickness bands apply to cut-length (not-in-coils) products under 720925–720928. Accurate gauge measurement at the time of entry is therefore essential for correct classification.

A cold-rolled flat product remains in heading 7209 only if it is not clad, plated, or coated. Once any metallic or non-metallic coating is applied — such as zinc, tin, aluminum, or paint — the product moves to heading 7210. The coating step typically occurs after cold-rolling and changes both the classification and, often, the applicable trade-remedy exposure.