Rawplug All Metal Self-Drill Plasterboard Fixings which fit flush to board and can be used in double thickness plasterboard. Will also provide a secure fixing into lightweight and aerated concrete blocks. (NOTE. an 8mm pilot hole is required for this fixing). For use only with the screws supplied. Max Fixture Thickness: 12mm (20mm Screw). Except RAW07130 Max Fixture Thickness: 35mm (25mm Screw).