Gas Flex 1/2" Tubing Pipe KIT 66ft with 2 Fittings gasflex The PE layers protect against corrosion and create a shield so tubing can be embedded in concrete The aluminum layer provides stiffness to hold the tubing in the desired shape and fire resistance. Together, the layers make up a flexible tubing that stays in place, very low thermal expansion rate. Expansion rate (similar to copper and steel). Attractive White Color