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