GOAL BL550 15 ft. Long Portable Bleachers 5-Rows Portable Bleachers feature galvanized steel understructure&#44; and anodized aluminum seats with non-skid Framework is heavy-duty galvanized steel&#44; robotically welded and hot dipped galvanized. Front and rear cross braces for stabilization. Seating is 2 D anodized aluminum with a .085 wall thickness. Non-skid surface&#44; smooth edge planks with end caps.