The HDS provides a straight line to space out the attachment points for the body, tail, and head. Choose the size based on the actual length mounted on the rod, since the wing and tail may extend well beyond the bend. Sizes 2 and 4 have a straight eye and are sold in packs of 20. Sizes 6, 8, 10, and 12 have a downward-sloping eye and are sold in packs of 25. All HDS hooks are made of high-carbon steel, chemically sharpened, barbless, and finished in Black Nickel.