The HDJ is designed for ball nymphs mounted on a standard wire jig hook. Check the ball before you start: make sure it moves smoothly over the bend and sits securely near the bent eye. The outer diameter alone is not enough to choose the right hook head; the width and shape of the slot also matter. Place the weight, then determine the remaining body length on the shank. The HDJ is chemically sharpened, barbless, and finished in Black Nickel, with 25 pieces per bag.