The processing process of {HEAD ~ the recessed hole} in {TAIL ~ the box end} of the wrench is also complicated  
in
The processing process of { HEAD ~ the recessed hole } in { TAIL ~ the box end } of the wrench is also complicated
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH