... 3.Grade:4.8 ,6.8,8.8..... Coupling Fasteners,Connecting Fasteners,Aluminum Fasteners. 1.What’s the specification of our Products ... ? MaterialCarbon steel,Stainless steel,Alloy steel,Copper,Aluminum are available.Carton steel is high quality iron,such as ... shiny brass , pure copper,such as H62,H65,H68...Aluminum is good Aluminum.Meanwhile,we can use other materials accordingto customer's ...