{HEAD ~ A groove} is formed in an endpiece head to allow distal ends of the head to flex away from the lens and reduce the pressure on {TAIL ~ the lens} 
{ HEAD ~ A groove } is formed in an endpiece head to allow distal ends of the head to flex away from the lens and reduce the pressure on { TAIL ~ the lens }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL