AirBake Ultra uses new MicroDome technology to decrease bake times by up to 15% over traditional insulated bakeware. With 100% aluminum construction and premium insulation, AirBake Ultra also promotes even baking, comes with a no rust promise, and allows virtually no chance of burning. It is the ultimate in insulated bakeware, and provides overall enhanced baking performance including better browning, no burning, and decreased bake times. Trapped air prevents the top sheet from overheating. Natural aluminum interior and exterior.