Hi FP! I can see you are trying to take a scientific approach to this which I can respect, especially since my education is based in science. For some of the people responding here I have an analogy for you which would explain your and my belief. I have collected for over 30 years, my two friends who are very knowledgeable and collected for 40 to 50 years each disagree on the gold TDS. Jim talked me out of buying one with a yellow backing; the other would only buy one with a yellow backing. The reason was their direct vet purchase experiences over the years. I think we believers have solid experience one way or the other. Those that do not have no experience with these over the years. In the helmet field we would say, �We agree to disagree� Best Wishes, Bob
