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