These hooks have the broadest size range within the Susan Bates family of hooks. Made of lightweight aluminum; each Silvalume hook undergoes a special anodizing process that etches away all surface impurities. In addition; each hook is heat treated for strength and durability and polished for a velvety smooth finish. Each size is color coded so you can find the size you need at a glance. Its famous in line head helps reduce wrist motion for fatigue free crocheting and helps you maintain a more consistent gauge.