BBI Cap Screw, Series: 1936/1960, UNC, 1/4-20, 1 in Overall Length, Round Socket Head, 3/8 in Head, Hex Drive, 3/16 in Drive, 180000 psi Tensile, HRC 38 - 43 Hardness, Heat Treated Alloy Steel, Grade: 3A, PlainBRIGHTON-BEST