ETFE, or ethylene tetrafluoroethylene, is a type of fluoropolymer that is known for its lightweight and durable properties. It is often used as a transparent covering material in architecture, allowing natural light to enter while providing excellent insulation. ETFE is resistant to chemicals, UV radiation, and extreme temperatures, making it suitable for various environments. One of the most notable applications of ETFE is in the construction of large structures, such as the Allianz Arena in Munich and the Eden Project in Cornwall. Its flexibility and strength enable architects to create innovative designs, while its recyclability contributes to sustainable building practices.