Heavy-duty industrial extension ladder. Features deeply serrated, 1-3/4 In. wide, flat type rungs. Modified I beam interlocking side rails are 3 In. wide. Has mar-resistant end caps and rail closures. Smooth operating pulley with polypropylene rope. Extruded rung locks with spring-activated nylon flipper. Shoes rotate easily and lock into spur position for penetrating grass and dirt. UL listed and labeled. Rope and pulley on 20 Ft. and larger only. Meets OSHA standards. TypeI heavy-duty industrial rating 250 Lb. load capacity.