Jaws are arguably the most important part of a vise. HMH's jaws are hardened tool steel so they will hold hooks well for years and years. And because access to the hook is the most important thing in fly tying, the shape and profile of all HMH jaw styles are carefully designed so that you can get to the hook with your fingers and position materials easily. Both magnum and micro have 30+ years of proven dependability and are Guaranteed for Life. Choose from magnum (hook sizes 12 to 10/0) or micro (hook sizes 18 to 32). Both sets of jaws are compatible with the SX, Spartan and Standard vise models.