Auto black bolts Grade:8.8,10.9,12.9 Material:carbon steel,35steeland customization Auto black boltsSpecification:1.Grade:8.8,10.9,12.92.Material:carbon steel,35steeland customization3.Surface:zinc plating,black,customized4.Colour:Gold,silver,yellow5.Technique:forging,rolled and grinding,punching Auto black bolts,bolts,black bolts,auto bolts,M.S.auto black bolts DIN933(4.8grade)