Stainless Steel by itself is a poor conductor of heat. On the other hand, aluminum is an excellent conductor of heat. It causes heat to diffuse all over the cookware uniformly. The Stainless Steel then does the job of retaining the heat. Your food comes in 0% contact with the aluminum so the cookware has no health risks associated with aluminum. Your cookware only utilizes the heat conduction benefits of aluminum while making sure your food does not come in contact with it. Stahl Cookware is 100% residue free, lead free and leach proof.