Grade: 4.8 8.8 10.9 Material: 45# Steel 40 Cr 35MoCr Finishing: Black Oxide Zinc Plated,phosphorization 1)Grade:Ordinary standard4.8 8.8 10.92) Material: 40Cr 45#steel,35CrMo..3) Finishing:Black Oxide, Zinc Plated, Phosphate,Dacromet,ect.4) Packing:Neutral export carton box. Pallets5) Metric and Imperial dimension are all available. Spring Center bolt,Bolt factory in China