Socket Head Cap Screw, Flat, Alloy Steel, Black Oxide Finish, Thread Size 1/2-13, Drive Type Hex Socket, Drive Size 5/16", Thread Type UNC, Thread Style Fully Threaded, Thread Direction Right Hand, Length under Head 1 3/4", Thread Length 1 3/4", Head Height 0.251", Head Dia. 0.938", Class 3A, Rockwell Hardness C38-44, Min. Tensile Strength (PSI) 180, 000, Package Quantity 50 RestrictionsNote: Thread lengths for partially threaded screws are minimum values; lengths may vary. Fully and partially threaded zinc-plated flat head cap screws are available on DrillSpot.com . Search for "fully threaded or partially threaded zinc-plated flat head cap screws". DrillSpot Approved VendorMin. tensile strength: 145,000 psi and up to 1/2"; 135,000 psi over 1/2" Rockwell hardness: C39 to C44 up to 1/2"; R37 to RC44 over 1/2"Camcar/Kerr LakesideMin. tensile strength: 145,000 psi up to 1/2"; 135,000 psi over 1/2" Rockwell Hardness: C38 to C44Alloy Steel Flat Head Cap ScrewsThread class: 3A, right-hand threads Meet ASTMF835/ANSI B18.3 standards