Sheetrock® Brand Mold Tough® VHI Firecode® X Panels (UL Type AR) are economical 5/8 in. Type X very high-impact-resistant (VHI) gypsum panels with moisture and mold resistance. These panels feature a proprietary fiberglass mesh embedded in a noncombustible core that's encased in 100% recycled moisture- and mold-resistant green face and brown back papers.