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