... A2,A4 4.carbon/mild/stainless steel... high strength hex bolts fasteners 1.Size:M1.6-M1002.Surface:black,phosphated,galvanized ... .. 3:Material:mild steel,45# steel,40Cr. High strength hex bolts fasteners(1)Grade4.8/8.8 A2,A4 (2)Surface ... , hot dip galvanized(3) Material:20MnTiB, 40CR(4)High strength bolts are widely used in industry, agriculture and structure.Packing: 1 ...