The HDG 645 features an elongated abdomen that follows the curve, followed by a thorax that is more pronounced at the front. Its straight eye is the key distinguishing feature compared to the HDG 644, which has a downward-sloping eye. For a midge larva or pupa, a slender body made of thread or segmented material maintains the hook’s profile. On a weighted Czech nymph, distribute the weight under the abdomen without creating a uniform bulge. This barbless hook has a Black Nickel finish and comes in packs of 25.