Aluminum pans provide even heat distribution as well as quick heating and cooling. Great for cooking large amounts of food. Easy to move around. 1.0 mm thick rim that prevents warping and keeps the pan flat. Each tray is 18 gauge commercial grade aluminum (beware of thinner models). The set includes 6 - three quarter sheet baking pans. Wire reinforced beaded rim helps prevent warping. Quick and even heating and cooling.