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