Sheet pans, baking trays or baking sheets are flat, rectangular metal pans used in an oven. They are often used for baking bread rolls, pastries and flat products such as cookies, sheet cakes, and swiss rolls. These pans, like all bakeware, can be made of a variety of materials, but are primarily aluminum or stainless steel. The most basic sheet pan is literally a sheet of metal. Common additional features that may be found in sheet pans include a lip on one or more edges to prevent food from sliding off, handles to aid in placing the pan into the oven, and removing it again, or a layer of insulation or air (air bake pan) designed to protect delicate food from burning.