It is furthermore of advantage for {HEAD ~ the inner thread} to have an inner diameter that diminishes with increasing distance from the free end of the cap towards {TAIL ~ its interior} 
It is furthermore of advantage for { HEAD ~ the inner thread } to have an inner diameter that diminishes with increasing distance from the free end of the cap towards { TAIL ~ its interior }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL