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