These silvalume hooks is made of lightweight aluminum | Each hook undergoes a special anodizing process that etches away all surface impurities | Each hook is heat treated for strength and durability and polished for a velvety smooth finish | These hooks famous in line head helps reduce wrist motion for fatigue free crocheting and helps you maintain a more consistent gauge | This set includes hooks in us sizes 4-mm, 5-mm and 6-mm