These hex head screws each feature a thick, hexagonal head designed for tightening with a wrench. - Use in pretapped holes or with nuts. Grade 5 steel construction offers strength and moderate flexibility. - The screws are hardened, yet more malleable than Grade 8, allowing them to withstand shear force. Material / Steel, Steel Material Grade/Class / Grade 5 Finish / Zinc Plated Thread Size / 5/16"-18 Thread Direction / Right Hand Fastener Length / 1 in Minimum Thread Length / 1 in Head Width / 1/2 in Head Height / 13/64 in Drive / Hex Drive Size / 1/2 in Tensile Strength / 105,000 psi Rockwell Hardness / HRC19 Dimensional Standards / ASME B18.2.1 Material Quality Standard / SAE J429 System of Measurement / Inch Overall Length / 1 in Thread Fit / 2A Thread Style / Fully Threaded Type / Hex Head Cap Screw Head Style / Hex Thread Pitch / Fully Threaded Thread Type / Coarse