Thermo-Flex is the Ultimate in Water and Fuel Line Protection.Thermo-Flex is the answer. Thermo-Flex is an universal heat shield that can be applied almost anywhere. Made from a lightweight composite material of aluminum, silica, and stainless steel, Thermo-Flex can withstand temperatures up to 1050°F. No need to disconnect existing lines. Thermo-Flex is very pliable, just slit it down the middle and slide it over the line.