The center opening 48 is preferably circular and has {HEAD ~ a raised lip} 50 around the circumference of {TAIL ~ the center} opening 48 
The center opening 48 is preferably circular and has { HEAD ~ a raised lip } 50 around the circumference of { TAIL ~ the center } opening 48
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH