5/16-18 GR2 HEX NUT HDG .017” SAE J995 GRADE 2 HEX NUT HDG ASME/ANSI B18.2.2 1987 IFI-7 AF 0.489-0.500” TH 0.258-0.273” – 100/BOX Tapped Over Size per ASTM A 153 class C