R4 MULTI-PURPOSE YZ SCREWS
GRK’s R4 self-countersinking screw has a patented underhead with saw-blade like patented cutting teeth and six self-contained cutting pockets. Together these features act like 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 enhances the R4’s versatility by allowing the fastener to countersink into even the hardest woods. The screw head closes the hole off with precision, leaving no damaged fibers around the head.
Because the head has a 90 degree angle at the underside, the screw fits perfectly into the pre-countersunk holes of hardware fittings such as hinges or locks. Stocking of different screws is no longer necessary because the R4 is a very versatile screw.