Hex Head Cap Screw System of Measurement Inch Basic Material Steel Material Grade Grade 8 Fastener Finish Zinc Yellow Dia./Thread Size 5/8 In.-18 Fastener Length 8 1/2 in Fastener Thread Direction Right Hand Fastener Thread Type UNF (Fine) Fastener Thread Style Partially Threaded Fastener Industry Standards ASME B18.2.1 Head Type Hex Min Thread Length 1 1/2 in Head Height 25/64 in Head Width 15/16 in Package Quantity 5