USG Sheetrock® Brand Mold Tough® Panels Firecode® Type X feature a noncombustible, moisture- and mold-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 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 Type SCX 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.