{HEAD ~ The cutting edges} of the reamer sections are parallel straight cutting edges or {TAIL ~ helical cutting edges} 
are
{ HEAD ~ The cutting edges } of the reamer sections are parallel straight cutting edges or { TAIL ~ helical cutting edges }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL