... 9.8..... Hollow Bolt,Stainless Steel Hollow Bolt,Bolt with Internal Thread.1.What’s the specification of our Products ? ... steel,Copper,Aluminum are available.Carton steel is high quality iron,such as 1022,1018,1010,1008,1015... ... head,Ball head,Button head... Socket typesPhillip type,Pozi type,Eleven type,hexagonal type,Torx type,trangle type,slotted point type,square type,Combined type... FinishZinc ...