All aluminum radiators begin with an aluminum "core", regardless of the brand or origin. The core is the most important part of any radiator because the quality of the radiator is dictated by the braze quality of the core section. The tubes must be bonded completely to the fin or heat transfer will suffer. All the tubes must be thoroughly brazed into the header plates or leaks will develop over time.
DeWitts Radiator is the only aftermarket radiator company that owns and operates an aluminum Nocolok brazing furnace. This allows them to build their own brazed aluminum radiator cores in house, so they control the quality of those cores. They know exactly what materials are being used and the brazing profiles. They do not purchase cores from others and assume they are quality parts.