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