Love this gauge! Granted you can use a caliper, but this makes it so much easier. No more guessing if your hole center on top or bottom of the shocks. Plus you can actually watch exactly how much your droop changes as you're tuning it. No more taking the wing off to adjust the rear either.
Setting and checking your droops is important. you can do this with calipers, but you have to remove the rear wing and it's hard to tell if you are in the center of the shock nut. This tool is fast and easy to use, it centers on the shock nut quickly and allows you to see what your droops are and adjust them if needed. As a plus you don't have to remove the rear wing to get accurate measurements.