... 8,8.8,9.8........ WAVE PLATE HEAD SCREW,DOUBLE HEAD SCREW,KNURLED HEAD SCREW A good non-standard fastenerS manufacturer ... :Generally,it is M1-M16 in our fasteners.The length :ordinary,It is less than 200mm .Threads/ Scrows ... 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 ...