If rayon (an artificial fiber) predominates by weight over the polyester (a synthetic fiber), the garment classifies under 610339 rather than 610333. The chief-weight determination is made fiber by fiber; importers should obtain a complete fiber-content breakdown from the manufacturer, since the predominant fiber governs the heading, and the secondary fiber content may then direct the entry to a specific 10-digit restraint line within 610339.

Line 6103394000 applies to garments of silk containing 70% or more silk by weight. Supporting documentation typically includes a manufacturer's fiber-content declaration and, for high-value shipments, an independent laboratory test report confirming the silk percentage. Entries that fall short of the 70% threshold would instead route to the appropriate NESOI line within the heading.