Thumb Screw Type Thumb Screw Finish Zinc Plated Material Iron Thread Size 5/16 In.-18 Fastener Length 3/4 in Head Width 1.25 in Head Height 0.66 in Tensile Strength - Head Type Wing Maximum Head Width 1.25 in Minimum Head Width 1.12 in Maximum Head Height 0.66 in Minimum Head Height 0.53 in System of Measurement Inch Head Material Iron Zinc Head Shape Wing