いろいろ 1/2-20unf thread 239411-1/2-20 unf 2a thread dimensions
ISO Fine Thread IX (metric) DIN 1310;ISO 2841 Spark Plugs Metric Threads Metric threads spark plugs according ISOUNF = Unified National Fine Screw Thread This is one of three graded series UNC (Unified National Corase); 4 40unc 1 2 unf Thread Plug Gage Go Nogo With Handle Class 2b Id 577 1/2-20 unf 2a thread dimensions