GRK's R4 self-countersinking screw has a new underhead with saw-blade like cutting teeth and six self contained cutting pockets. The screw head closes the hole off with precision, leaving no damaged fibers around the head. The R4 is available in 59 sizes from #4 by 3/8-inch to #12 by 12". This multi-use screw can be used in wood, particle board, plastic, sheet metal, cement fiberboard, composite decking, wood decking and melamine. Some sizes are also available in PHEINOX stainless steel.
GRK's R4 self countersinking screw has a new underhead with saw-blade like cutting teeth and six 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. This design also further enhances the R4's versatility by allowing the fastener to be installed without countersinking into even the hardest woods. The screw head closes the hole off with precision, leaving no damaged fibers around the head.