GRK's R4 self-countersinking screw has a patented under head with saw-blade like cutting teeth and 6 self-contained cutting pockets. Together they act similar to a circular saw-blade, transporting the drill dust away from the edge of the screw hole while cutting a perfectly clean hole into even the most brittle materials without cracking any surface treatment. R4 Multi-Purpose Framing Screws are used for wood, plastic, cement fiber board, particle board, sheet metal, wood decking and melamine. For use in all applications that include pressure treated lumber.