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