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5/8 in. (15.9 mm) Sheetrock ® Brand EcoSmart Panels Mold Tough ® Firecode ® X (UL Type ULIXTM) represent a revolution in wallboard manufacturing, reducing the use of natural resources and impact on the environment. These lightweight 5/8 in. (15.9 mm) enhanced proprietary Type X gypsum panels feature a noncombustible, moisture-resistant gypsum core that is encased in moisture- and mold-resistant, 100% recycled green face and brown back papers. When tested in accordance with ASTM D3273, Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber, the panels meet or exceed ASTM C1396 specifications. The face paper is folded around the long edges to reinforce and protect the core, and the ends are cut square and even. The long edges of the panels are tapered, allowing joints to be reinforced and concealed with USG Sheetrock ® Brand joint treatment systems. The panels are UL Classified for fire resistance and can be used in any UL Design in which UltraLight Innovation Type X (ULIXTM) panels are listed. On the face along the long edge of each panel, the UL Type Designation is printed for easy identification by building inspectors.