Straight Stair Elevation Detail . 1¼ "diameter stainless steel metal tube, matt finish, metal handrail in stainless steel exit hall 1¼ "in diameter (see fastening detail)., Alfarda formed with hardboard panel of durock of 1/2 "Pan American gypsum plaster, covered with tepexi marble of 1'x1 ', 3/8" thick, matt finish.