{TAIL ~ The extension} has an inner diameter less than {HEAD ~ the inner diameter} of the remainder of the annular protrusion 
{ TAIL ~ The extension } has an inner diameter less than { HEAD ~ the inner diameter } of the remainder of the annular protrusion
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH