The Fish-Skull is designed to mimic the head, eyes and gill plates of baitfish patterns. These heads are made of a lightweight, corrosion-resistant metal alloy that avoids adding excessive weight (about the same as dumbbell eyes). The center of gravity is kept below the hook shank, providing a "keel" whether the pattern is tied with the point above or below the shank. 3-D adhesive eyes are included in the package as an option to stick in the recessed eye sockets. The head has a slot on the front, allowing you to slide the head over the eye of the hook after all other material is tied. The sizes are matched with hook sizes from as small as 10 up to 4/0.