The collapsible position occupies less volumetric weight as compared to the fully extended position so as to reduce the volumetric weight when {HEAD ~ the backframe} is in {TAIL ~ transportation} and storage 
The collapsible position occupies less volumetric weight as compared to the fully extended position so as to reduce the volumetric weight when { HEAD ~ the backframe } is in { TAIL ~ transportation } and storage
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH