If we had to guess, the "GD" in Ergon GD1 Evo Grips is short for "go down." As in, go downhill very rapidly, with superior grip and control. These grips aren't just any old tubes of rubber you haphazardly put on your bars, these are high level asymmetrical ergonomic control devices, with careful attention paid to compounds, shapes, and feel. Give your hands a break and check them out.