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