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