Injen set out to develop the ultimate filter design, and they have come up with the Injen Universal Filter. After extensively testing rubber and plastic compounds they came upon a urethane rubber that is able to withstand elevated temperatures with zero distortion. Urethane is a light weight material which will not fade and will hold its shape for the life of the filter. Injen pioneered the technique of incorporating the built-in velocity stack in the filter base. Injen Technology filters have been tested repeatedly on a flow bench and on a dynomometer against the leading competition's filter elements and have out-performed them every time. Based on these test results it's no wonder that the competition has taken steps to duplicate Injens filter design utilizing their techniques in molding urethane compounds.