Sheet pans or baking trays (British English) are flat, rectangular metal pans used in an oven. They are primarily used for baking 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 an insulated bottom designed to protect delicate food from burning.