This doesn't even look like a tuner to me, but a very useful thing when initially setting up the diaphragms. Since it is a device that measures the tension of the membrane at the place where it is placed. You have to learn to deal with it, sometimes you just need to place it on the membrane a little stronger or weaker or a little further from the edge of the drum, and you have completely different values. As a tuner, I'm not sure. If you have a different experience, feel free to confront me. But I say, a useful sensitive thing for the initial installation of membranes.