GRK’s R4™ self-countersinking screw has a new under head with saw-blade like 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 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. R4™ screws which are 50mm and longer have a four threaded CEE thread that enlarges the screw hole for the non-threaded portion of the fastener. This technological advancement allows the wood to settle easily and increases the screw’s drawing strength, reducing the friction on the screw shank and lowering the driving torque.