I had three different chain wear indicators, including a Wipperman. They all give inconsistent readings with each other. So I bought the Birzman, which does not seem to agree with any of them. How do I know which one to rely on? I am going to go by the most conservative one, the Wippermann. It is by far the longest, whereas the Birzman is the shortest. Cannot understand how an eccentric pin is going to be accurate enough to detect such minute tolerances over such a short length. So, I give it the benefit of the doubt with 4 stars. But it could be 1, or 5. I have no way of checking.