GRK RSS Rugged Structural Screw has a patented design and made of especially hardened steel to provide customers with high tensile, torque and shear strength. The sharp threads and points bite instantly into material, including hardwood, reducing the splitting effect due to smaller shanks. The GRK RSS series screws that are 3-1/8 in. and longer have six CEE threads which enlarge the screw hole for the non-threaded portion of the fastener, allowing the wood to settle easily and increases the screw’s drawing strength.