The primary advantage of aluminum bakeware is that it responds quickly to changes in temperature. heating up and cooling off quickly and spreading heat evenly throughout the pan. This ensures that baked goods cook evenly wherever on the pan they are. And of course, aluminum does not corrode or rust and it's lightweight. Aluminum bakeware is the choice of professional bakers for these very reasons. These two cookie sheets are ideal for cookies of all kinds, including bar cookies. We recommend the use of parchment papeer or a silicone baking sheet (pictured) to ensure the easy release of cookies from these pans.