fiber, the purpose of the intake is to increase air flow and also to keep it cool. both of the products use cone filters. ECIS uses a heat shield to guard against the heat while the Dinan isolates the filter in the brake duct area. This setup leaves it hard to manage as far as maintainence is concerned. You have to remove the headlight assembly i believe to remove the filter for cleaning. I have the ECIS in my car and i am very satisfied with the results. i was skeptical about the heat shield at first but after hours of driving, there is a significant difference in temperature. I don't think that 400+ dollars is worth it for an intake.