Flex Fuel U.S. ®, a leading pioneer in ethanol conversion systems, has developed the Flex-Box Smart Kit™, a first-of-its-kind after-market bolt on fuel conversion system. The system is the first and only E85 conversion unit has been certified by the Environmental Protection Agency (EPA) for fleet vehicles, and allows fleet operators and drivers to fill up on E85 (a blend of 85 percent ethanol and 15 percent gasoline) E20, E10 or pure gasoline.