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