The clamp plate extension has {HEAD ~ a concave, circular toothed depression} forming {TAIL ~ one half} of a socket to hold a ball 
forming
The clamp plate extension has { HEAD ~ a concave , circular toothed depression } forming { TAIL ~ one half } of a socket to hold a ball
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH