For over 20 years, GRK has produced contractor-grade fasteners for professional use, incorporating innovative design features to make screws that are faster and easier to drive, hold better in wood, plastic and composite materials, and reduce the risk of splitting.
These screws have a pattern of cutting ridges on the underside of the head to automatically countersink the screw. Self-tapping tips eliminate the need for pre-drilling; all except the 1" screws have sawtooth-like ridges on the threads near the tip to reduce friction and driving effort. Secondary threads enlarge the upper portion of the hole slightly so the screw seats snugly with less torque.
The screws have Torx heads (and are supplied with a matching Torx bit) to reduce the potential for cam-out and slippage in the drive. The hardened steel screws have a rust-resistant Climatek coating that won't react with treated lumber; the 305 stainless-steel versions have a Pheinox coating for additional long-term corrosion resistance in marine environments, below-ground use or other harsh conditions.