Rawlplug® UNO® Plugs are truly universal plugs which fix into any wall, ceiling or floor. Suitable for use in: concrete, brickwork, stone, blockwork, plasterboard. They have a unique design with expansion throughout the length of the plug. They expand at the top giving instant grip. Anti-rotation features prevent spinning in the hole. Screw Head Size:Yellow: 3-4.5mmRed: 3.5-5mmBrown: 4-6mmBlue: 4.5-6mmGrey: 5-8mm Typical Applications: - Shelving and cabinets- Suspended ceilings- Switch boxes- Trunking and cable trays- Water heaters and radiators