One of the largest volume processes for extrusion within the plastics industry is the production of sheets and films. Many products are needed in sheet form, or at least start out as a sheet and undergo postprocessing afterward. Common examples are roll roofing, packaging films, flexible printing plates, filtration membranes, agricultural films and tarps, frozen dinner trays (thermoformed from sheets), building insulation, kitchen countertops, battery separators, various sheets for electronics applications, interior and exterior panels for automobiles, photographic and x-ray films, etc.