It is also preferred that the cap is resilient and is slightly larger in diameter than {HEAD ~ the internal diameter} of {TAIL ~ the hollow} 
of
It is also preferred that the cap is resilient and is slightly larger in diameter than { HEAD ~ the internal diameter } of { TAIL ~ the hollow }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL