The insert has two arms that each extend from {HEAD ~ the intersection} of {TAIL ~ imaginary extensions} of the secondary locating sides 
of
The insert has two arms that each extend from { HEAD ~ the intersection } of { TAIL ~ imaginary extensions } of the secondary locating sides
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH