Insulated Box Liners by Cool Blue fold down for easy storage, taking up less warehouse space and reducing your inbound freight charges. Cool Blue insulation acts like a shield against the three types of heat transfer, conduction, convection and radiant. Foil reflects 97% of radiant heat. Heat reflecting technology outperforms foam, takes up a fraction of space, and costs less. Dirt smudges show easily on foam, while Cool Blue's shiny exterior provides a clean and pleasant presentation. Foil Insulated Box Liners - Size: 8.5" x 1.5" x 5.25". Fits USPS Small Flat Rate Boxes.