... .Grade:4.8 ,6.8,8.8,9.8..... Hollow Bolt,Stainless Steel Hollow Bolt,Bolt with Internal Thread.1.What’s the ... ,CH38F,1039,40ACR...Alloy steel are 35,40CrMo,SCM435,10B38...Stainless steel is SS201,202,302,304,316...copper is shiny ... type,hexagonal type,Torx type,trangle type,slotted point type,square type,Combined type... FinishZinc plated,Nickel plated,Dacroment Plated,chromium ...