This is a unique short shank wide gap hook that has a medium wire. It was originally designed for foam ants and beetles, but it works very well as a nymph hook and is one of my personal favorites in my nymph box.
NOTE: The shank on these hooks is very short. Each hook is a full size smaller than its labeled size. For instance, the 18 is a legitimate 20 in other models/brands of hooks, the 16 is an 18, etc.