Designed for ceiling or duct shaft and composed of 1” (25.4 mm) ToughRock® Shaftliner or DensGlass® Shaftliner panel supported by 2-1/2” (64 mm), 4” (102 mm) or 6” (152 mm) C-T studs and three layers of 1/2” (12.7 mm) ToughRock® Fireguard C® or 1/2” (12.7 mm) DensArmor Plus® Fireguard C® gypsum board.