Base Layer: 1/2” (12.7 mm) ToughRock® Fireguard C® gypsum board tied to W10 x 49 (metric W250 x 73) column 1 hr. with 18-gauge (43 mils) wire 15” (381 mm) o.c. Face Layer: 1/2” (12.7 mm) ToughRock Fireguard C gypsum board applied with laminating compound over entire contact surface. Test conducted with generic Type X in December 1952. Contact GP Technical Service Hotline for a copy of the test report.