Gates 91107 Belt Tension Tester

As I don't have anything to compare it to, I am unsure of the accuracy. You push on a "clicker", like a child's toy and then read a scale. It is not a "high resolution" tool but it is not expensive and I will give it a try. Of course one can get a ballpark estimate by judging the distance pushed with a finger. I guess I like the idea of a second estimate... I would be curious what professional mechanics think but I guess they are used to estimating by "feel".