... 9.8........ WAVE PLATE HEAD SCREW,DOUBLE HEAD SCREW,KNURLED HEAD SCREW A good non-standard fastenerS manufacturer ... threads "A","AB", Threads for chipboard screw,wood screw,drywall screw;Type "M","UNC","UNF","BSW"threads for ... manufacturer with more than 20 years experiences in screw,bolt,nut,washer,rivet, stud, pin,wrench ... material are always use C1022 ,The percent C element is 0.18%-0.23% ,is higher ...