A threaded mandrel goes through {HEAD ~ the hole} in {TAIL ~ the top} of the cup shaped member and engages the expander member of the rib plug 
in
A threaded mandrel goes through { HEAD ~ the hole } in { TAIL ~ the top } of the cup shaped member and engages the expander member of the rib plug
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH