{TAIL ~ The proximal ends} of {HEAD ~ the inner and outer tubes} are conventional and do not form any part of this invention 
{ TAIL ~ The proximal ends } of { HEAD ~ the inner and outer tubes } are conventional and do not form any part of this invention
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH