{HEAD ~ An apparatus} for simultaneously forming a plurality of closely spaced, parallel grooves having {TAIL ~ a web} between them in a thin walled tube is described 
{ HEAD ~ An apparatus } for simultaneously forming a plurality of closely spaced , parallel grooves having { TAIL ~ a web } between them in a thin walled tube is described
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH