... 8 ,6.8,8.8,9.8..... Hollow Bolt,Stainless Steel Hollow Bolt,Bolt with Internal Thread.1.What’s the specification of our ... customer's demand .Threads/ScrowsType "M","UNC","UNF","BSW"thread are available. Head typesHexagon head,Mushroom head,Pan head,Countersunk ... head,Bugle head,Oval head,Hex flange head,Round head,Ball head,Button head... Socket typesPhillip ...