We now stock competitively priced PEX-AL Oxygen Barrier (OB) tubing in 1/2" ID in 300 M (985') long rolls to be used with our XPS-AL panels. One roll should be sufficient for four 120 SF bundles of panels. Although PEX-B has become the most popular tubing in North America for radiant heating applications, this is largely due to its lower cost compared to the other two types available. https://thermatlantic.com/pex-....al-tubing-1-2-id-x-3