In fact, the holes 50 can be formed with {HEAD ~ threads} to receive {TAIL ~ the inserts} 
In fact , the holes 50 can be formed with { HEAD ~ threads } to receive { TAIL ~ the inserts }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL