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