Silver Foil Bubble Mailer Envelopes 6" X 9" - 100/Case Foil Bubble Mailers by Cool Blue costs less than traditional foam and ideal for cold shipping. Foil reflects 97% of radiant heat and acts like a shield against three types of heat transfer: conduction, convection and radiant. Costs less than traditional foam insulation. Bubble laminated for durability and protective cushioning. 100/Case.