The height of thread crest of {HEAD ~ the smaller diameter parallel thread part} 15 is as small as {TAIL ~ about 0.1 mm} 
The height of thread crest of { HEAD ~ the smaller diameter parallel thread part } 15 is as small as { TAIL ~ about 0.1 mm }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL