... 6.8,8.8,9.8... CYLINDER HEAD SCREW,BRASS COPPER DECORATIVE SCREW,SMALL SCREW . A good non-standard fastenerS ... 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, ... 0.23% ,is higher hardness than other.2.Fasteners' Head is much thicker ,it is strong not break down . ...