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