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