We developed many aluminum staircases, and this kind is square-tube fixed aluminum climbing ladder, processed by 30*45*3 aluminum alloy square tube, color of oxidation on the surface of square tube, steps on the steps use 30*30*3 aluminum which is with antiskid square pipe
http://www.jlfiretruck.com/aluminum-staircase/square-tube-aluminum-staircase/square-tube-fixed-aluminum-staircase.html