Shrink Tunnel is a heated tunnel that is positioned above or all around a conveyor system. Shrink film is placed loosely on items (such as packing); when heated, the material contracts to tightly enclose the wrapped object. The heat source may be an electrical resistance heating element, an infrared heater, steam, or a gas flame. Shrink Tunnel is frequently utilized to enhance convection, sometimes concentrating the heat on one area of the object.