... quality iron,such as 1022,1018,1010,1008,1015...Medium carbon steel are 35k,45#,10B21,1035,CH38F,1039,40ACR...Alloy ... head,Countersunk head,Bugle head,Oval head,Hex flange head,Round head,Ball head,Button head...Socket typePhillip type,Pozi type ... manufacturer with more than 20 years experiences in screw,bolt,nut,washer,rivet, stud, pin,wrench and so on .2.Our ...