Teflon® FEP, Tefzel ETFE closure. Combine the excellent chemical resistance of Teflon® FEP with the convenience of a screw closure. Theyáre unbreakable, nearly transparent, non-contaminating, and resist virtually all chemicals. Withstand temperatures from - 270 to + 205 °C; closures from - 100 to + 150 °C. Can be autoclaved or chemically sterilised repeatedly. Before autoclaving, just set cap or closure on top of the container without engaging the threads. Useful with all organic solvents, concentrated oxidising agents. Can be boiled in concentrated nitric acid for trace metal work.