When the retractable/deployable bolster is retracted the closure mechanism is positioned over {HEAD ~ the retractable/deployable bolster} to prevent {TAIL ~ the retractable/deployable bolster} from protruding from the top surface 
to prevent
When the retractable / deployable bolster is retracted the closure mechanism is positioned over { HEAD ~ the retractable / deployable bolster } to prevent { TAIL ~ the retractable / deployable bolster } from protruding from the top surface
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH