Many people use Aluminum cookware because it heats faster. But there have been studies indicating that some Aluminum gets into the food, and it may not be good for your health. A solution is to use stainless steel cookware. Waterless cookware is made of high grade stainless steel to protect the food from leaching or tastes from contact with metal. Stainless steel is also easier to clean and does not require such coatings as Teflon, which also may get into the food.
Some companies advertise that they use surgical stainless steel.
All that means is that it is the highest grade. It is more about marketing than cooking. The bottom of the cookware is machined flat so that as much surface as possible is in contact with the coils, when using an electric stove. The surface is also machined for better efficiency when using a gas stove. Bottom plate used to evenly distribute heat An aluminum or copper plate distributes the heat evenly along the bottom of the pot or pan.