It also forces the radially extending rings through {TAIL ~ the sealing material} and into contact with {HEAD ~ the surrounding tubular} 
It also forces the radially extending rings through { TAIL ~ the sealing material } and into contact with { HEAD ~ the surrounding tubular }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD