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