The description of the item 7410210050 of France HScode: "Refined copper foil, backed, of a thickness ""excl. any backing"" of <= 0,15 mm (excl. stamping foils of heading 3212, metal yarns and metallised yarns and foil made up as christmas tree decorating material) : Plates: -consisting of at least one layer of fibreglass fabric impregnated with thermosetting resin, -covered on one or both sides with copper foil with a thickness of not more than 0,15 mm, and -with a dielectric constant (DK) of less than 3,9 and a loss factor (Df) of less than 0,015 at a measuring frequency of 10 GHz, as measured according to IPC-TM-650"