12.9 bolt grades: 1.Spec:DIN,JIS,ASTM,GB,UIC 2.Surface:black, HDG 3.Grade:4.8,8.8,10.9,12.9 4.Material ... :Q235,45#,40Cr ASTM DIN GB Standard High strength 12.9 bolt grades with large hexagon ... head for steel structures I. Item:High strength bolts for steel structuresII. Specification: DIN 6914, DIN 6916, DIN ...