From the Manufacturer: Blue Monster thread sealing tape is manufactured from PTFE resin, a polymer consisting of recurring tetrafluoroethylene monomers. It is inert and compatible with a very wide range of materials. Use Blue Monster on threads made from galvanized steel, iron, brass, copper, aluminum, stainless steel, polyethylene, polypropylene, PVC, CPVC, ABS, fiberglass and more. Compatible with a broad range of gases and liquids as well as piping materials. Blue Monster is rugged and has not been stretched during the manufacturing process, so it is thicker and creates a more effective seal with less tape, and no need for pipe dope.