An adjustable back leg assembly provides {HEAD ~ a step ladder} of {TAIL ~ simple construction} for convenient use on stairs and other sloping surfaces 
An adjustable back leg assembly provides { HEAD ~ a step ladder } of { TAIL ~ simple construction } for convenient use on stairs and other sloping surfaces
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH