5ata, I looked at the link. "Composite" is another, fancier word, for plastic. Fiberglas, used in plastic boats, cars, etc, is a composite. Do you have any data comparing the actual thrust numbers or in water speed trials of any of these long fins? There was a one man test reported in the Australian website, Divernet, but I would think that, if the fins (any long fins) performed as claimed, that there would be something comparable to the Scubalab test which tested one new type of long fin against the Tre and others, and the long fin came in dead last. That compares favorably with my informal tests of the same fins. The swimmers who participated in that test were of impeccable reputation. There was even one Olympic athlete, if I recall correctly. I wish Dr Jim Greer would take up the cause. At least one could believe in the results and not have to rely on testimonials from factory sponsored divers and from other commercial interests.