Metal Staircase suppliers Theory Igreats offers fully prefabricated spiral staircases that require no assembly. Treads, railings, spindles, and pole are welded together to form an extremely sturdy one-piece spiral stair that is shipped ready for installation. Specification itemvalue Warranty5 years After-sale ServiceOnline technical support, Onsite Installation, Onsite website:http://www.tjigt.com/wrought-iron-balustrade/metal-staircase/