Machine Screw Head Type Round Material Steel Finish Zinc Plated Drive Combination Slotted/Phillips Thread Size 5/16 In.-18 Fastener Length 2 1/2 in Head Width 0.579 in Head Height 0.198 in Drive Size #3 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 100