The Belly Bumper Hook is similar to the old Mustad 79666 Keel Hook that went out of production many years ago.  This hook is a little different in two respects: First off, it has a little deeper gap than the original so you have a little more room to play with.  The second, and probably the most important, is that features a vertical ring eye so that your flies always track the way you intended them to.  Available in Size #2/0 – #4.