An expensive, semi-crystalline, melt processable thermoplastic that is essentially a 1:1 alternating copolymer of ethylene and tetrafluorethylene. It has a very high impact strength even at low temperatures and is relatively stiff by fluoropolymer standards, but its chemical resistance, though good, is not as good as that of PTFE.

It is used for chemical apparatus and process equipment, vessel linings and wire coatings.