Sheetrock® Brand UltraLight Panels Firecode® X (UL Type ULX) are the industry's first lightweight 5/8 in. Type X panels available. Formulated to achieve all of the strength and performance characteristics as standard 5/8 in. Sheetrock® Brand Firecode® Panels at a significantly reduced weight, these panels feature a noncombustible gypsum core encased in 100% recycled face and back papers, are UL Classified for fire resistance and can be used in any UL design in which Type ULX panels are listed.