What is an aluminum "sandwich" bottom and why is it important to have one?

Kuhn Rikon combines the excellent qualities of stainless steel with the superior heat conductivity of aluminum to obtain cookware with the benefits of both metals. First, the stainless steel pan is formed, then a 1/4" thick disc of aluminum is then affixed to the bottom of that pan. A disc of stainless steel completes the "sandwich" on the bottom of the pan. This final stainless steel disc is affixed both because it creates a more aesthetically pleasing piece and because stainless steel, being smoother and less porous than aluminum, is easier to clean and is non-abrasive to ceramic cook tops. The aluminum never touches the food being cooked.