... 9.8..... Hollow Bolt,Stainless Steel Hollow Bolt,Bolt with Internal Thread.1.What’s the specification of our Products ? MaterialsCarbon ... customer's demand .Threads/ScrowsType "M","UNC","UNF","BSW"thread are available. Head typesHexagon head,Mushroom head,Pan head,Countersunk ... Rich Experience ,good technology1.We are a professional manufacturer with more than 20 years experiences in screw,bolt,nut, ...