BLACK on one side to Mask stray lighting leaks. An all weather aluminum foil tape for general purpose use. It is a dead soft high tensile 2 mil thick aluminum foil coated with an aggressive acrylic adhesive system on a removable paper liner. Its malleable foil conforms well to irregular and curved surfaces; and will perform well at both low and elevated temperatures. It can also be applied at low temperatures. JVCC AF20 Foil Tape is used for vapor barrier protection, waterproof sealing, heat reflection & dissipation, masking in paint stripping and electroplating, and sealing plastic automation plateware for use in biotechnology research. The wider width 3 and 4 inch is also used to cover over and seal seams in Hexayurt shelters.