GRK R4 Multi-Purpose Screws are self-tapping with a countersinking head. They require no pre-drilling. This self-countersinking screw has a new underhead with saw-blade like cutting teeth and six self-contained cutting pockets. This transports the drill dust away from the edge of the screw hole while cutting a perfectly clean hole without cracking the surface. The screw head closes the hole off with precision, leaving no damaged fibers around the head. The R4 is available in 59 sizes and works well in wood, particle board, plastic, sheet metal, cement fiberboard, composite decking, wood decking, and melamine. Some sizes are available in PHEINOX Stainless Steel.