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