British Gypsum 19 mm Coreboard one layer., British Gypsum 15 mm Glasroc F FIRECASE one layer., British Gypsum 20 mm Glasroc F FIRECASE one layer., British Gypsum 25 mm Glasroc F FIRECASE one layer., British Gypsum 30 mm Glasroc F FIRECASE one layer., British Gypsum 19 mm Coreboard two layers., British Gypsum 15 mm Glasroc F FIRECASE two layers., British Gypsum 20 mm Glasroc F FIRECASE two layers., British Gypsum 25 mm Glasroc F FIRECASE two layers., British Gypsum 30 mm Glasroc F FIRECASE two layers.