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