Dynamic cold resistance (flexing) is a limitation for most geomembranes. When a robust geomembrane is needed, XR-5® is the answer, but only now has a new product been developed that expands the cold weather window for installation. The modified XR-5 compound retains the broad chemical resistance of the proven product and is coated on the same heavy base fabric. The result is the history and experience of the XR-5, now in a ULT version. The XR-5 ULT remains flexible to temperatures 11 degrees Celsius lower than standard XR-5, making it the choice for very cold installations. Factory-fabricated XR-5 ULT panels can be shipped to the jobsite and unfolded and installed at lower temperatures, expanding the installation season.