Certainly they know more than I. However, I don't know any of them. Fins can be expensive, so if I think one needs a thinner foil, I'm sanding it down myself. I just couldn't afford to buy a new one if I wanted to alter the one I'm using. In fact I just sanded one to thin the foil. Sailing with it, I know it didn't hurt and may have helped. Whatever, I had a great day of sailing!!! I hope you have many like it.