Cool Blue Foil Bubble Mailers, 4" x 5" - 10 Per Case Ideal for overnight mailings Extra protection! 5/8" foil laminated metalized bubble cushion with self seal adhesive strips Foil insulation acts like a shield against three types of heat transfer: conduction, convection and radiant. Foil reflects 97% of radiant heat Use with Gel Blox Cooler & Shipping Packs Cool Blue Foil Bubble Mailers - 10 Per Case (Inner Dimensions are 4" x 5")