Machine Screw Head Type Flat Material Brass Finish Plain Drive Slotted Thread Size 5/16 In.-18 Fastener Length 1 1/2 in Head Width 0.579 in Head Height 0.191 in Tensile Strength 60 000 psi Dimensional Standards ASME B18.6.3 Pack Size Small Type Standard Machine Screw Maximum Head Width 0.579 in Minimum Head Width 0.556 in System of Measurement Inch Thread Type Coarse Package Quantity 25