{HEAD ~ The backframe} can be switched from {TAIL ~ a fully extended position} under normal use, or a collapsible position under a transportation or storage 
switched from
{ HEAD ~ The backframe } can be switched from { TAIL ~ a fully extended position } under normal use , or a collapsible position under a transportation or storage
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH