... threads for Machine threads.Head typesHexagon head,Mushroom head,Pan head,Countersunk head,Bugle head,Oval head,Hex flange head,Round head,Ball head,Button head...Socket typesPhillip type,Pozi ... technology1. We are a professional manufacturer with more than 20 years experiences in screw,bolt,nut,washer,rivet, stud, ... 1.The material are always use C1022 ,The percent C element is 0.18%-0.23% ,is higher ...