The outer fins 2 wind and extend around {HEAD ~ the outside surface} of {TAIL ~ the tube body} 1 in helical manner 
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The outer fins 2 wind and extend around { HEAD ~ the outside surface } of { TAIL ~ the tube body } 1 in helical manner
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH