1.Material:40Cr 2.Surface Finished::Black Oxile and zinc Plating 3.Size:Dia M6-M42 4.Grade: 8.8,10.9,12.9 5.OEM service 1.Product informationProduct nameHex boltSize1/4,5/16,3/8,M6,M8,M10 seriesClass4.8,6.8,8.8,etc.Grade2,5,8,10,etc.MaterialLow carbon steel,stainless steel,alloy steelFinishBright,zinc plated,hot-dip galvanized,mechanical plating,black,dacroment etc.ColorNatural color,zinc color, ...