Upon {HEAD ~ expansion} of {TAIL ~ the underlying base ring}, the inserts break through the sealing material and penetrate the surrounding tubular to enhance grip when high differential pressures are encountered 
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Upon { HEAD ~ expansion } of { TAIL ~ the underlying base ring } , the inserts break through the sealing material and penetrate the surrounding tubular to enhance grip when high differential pressures are encountered
OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH