GRK’s R4™ self-countersinking screw has a patented 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 enhances the R4™’s versatility by allowing the fastener to countersink into even the hardest woods. The head of the screw closes the hole off with precision, leaving no damaged fibers around the head.

R4™ screws 3-1/8” and longer have a four threaded CEE Thread. This enlarges the screw hole for the non-threaded portion of the fastener, allowing the wood to settle easily. It increases the screw’s drawing strength and reduces the friction on the screw shank that lowers the driving torque.

Fast Bite Tip: Eliminates pre-drilling and provides a fast start for one-step installation.
W-Cut™: Low torque, faster drive.
Precision Fit: Reduces wobble between R4 screws and GRK bits for improved productivity.
Star Drive: Zero stripping, with 6 points of contact.
Optimized Thread Length: Improves clamping force for increased drawing power
CEE Thread: Enlarges hole to reduce splitting.
Cutting Teeth: Cuts wood fiber & provides flush seating.
GRK Head Markings: Easy identification of genuine GRK screws.
ESR-3201 Approved for structural applications.
Climatek™ Coating is AC257 code approved for use in treated lumber.
For interior / exterior use in; wood, plastic, cement fiber board, particle board, sheet metal, wood decking and melamine.
Also available in PHEINOX™ 305 and 316 grade Stainless Steel.