{HEAD ~ A cover} is disposed over the membrane and is sealingly engaged with the body to accommodate axial sliding movement from {TAIL ~ an outer position} to an inwardly displaced position 
{ HEAD ~ A cover } is disposed over the membrane and is sealingly engaged with the body to accommodate axial sliding movement from { TAIL ~ an outer position } to an inwardly displaced position
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH