Socket Head Cap Screw, Head Style Button Head, Alloy Steel, Finish Black Oxide, Thread Size 5/16-18, Drive Type Hex Socket, Drive Size 3/16 In, Decimal Equivalent 0.188 In, Thread Type UNC, Thread Style Fully Threaded, Thread Direction Right Handed, Length under Head 3/8 In, Thread Length 3/8 In, Head Height 0.166 - 0.152 In, Head Dia 0.547 - 0.527 In, Class 3A, Rockwell Hardness RC 38-43, Min Tensile Strength 180, 000 PSI, Meets/Exceeds ASTM A574/ANSI B 18.3, Package Quantity 100 RestrictionsNote: Thread lengths for partially threaded screws are minimum values; lengths may vary. Zinc-plated are available on DrillSpot.com . DrillSpot Approved VendorTensile strength: 135,000 psi up to 1/2"; 145,000 psi over 1/2" Rockwell hardness: C39 to C44 up to 1/2"; RC37 to RC44 over 1/2"Camcar/Kerr LakesideTensile strength: 145,000 psi up to 1/2"; 135,000 psi over 1/2" Rockwell hardness: C38 to C44 (Camcar) RC37 to RC43 (Kerr Lakeside) Thread class: 3AAlloy Steel Button Head Cap ScrewsMeet ASTM F835/ASME B18.3 standards.