CIRCULAR STAIR WITH BOX STRINGERS MADE OF C 12 X 20.7 AND 1/4” X 12” COVER PLATE. INTERIOR STRINGER FLARES TWO FEET WIDER THAN AT THE TOP. COMBINATION RISER/TREAD TYPE 4. FULLY SHOP WELDED AND INSTALLED IN ONE PIECE. THE ENTIRE STAIR WAS ENCASED WITH MARBLE.