Cole-Parmer® XRF window film serves as the sample window over our X-Cell sample cups, allowing for uniform transmission of x-rays while effectively containing the liquid sample. BoPET film is heat resistant up to 100 °C (212 °F). Unusually strong for its thickness, it is resistant to organic chemicals but vulnerable to strong acids and bases. It may contain trace levels (ppm) of Ca, P, Fe, Cu, Zn, or Sb.