Wikipedia
ETFE
Ethylene tetrafluoroethylene (ETFE) a fluorine-based plastic. It was designed to have high corrosion resistance and strength over a wide temperature range. ETFE is a polymer and its source-based name is poly(ethene-co-tetrafluoroethene). ETFE has a relatively high melting temperature, excellent chemical, electrical and high-energy radiation resistance properties. When burned, ETFE releases hydrofluoric acid.