Mechanics extension flat D rung loading ladder. 1-3/4 In. flat-top rung. 3 In. stacked full I beam rails. Up to 32 Ft.:3/4 In. flange. 32 Ft. thru 40' Ft.: 7/8 In. flange. Free sliding glides. Die-cast aluminum spring-loaded gravity locks. Locks fully engage 2 Twist Proof performance-type rungs. 5/16 In. polypropylene continuous rope. Heavy-duty shoes. Only 6 In. to ground from first rung. UL listed and labeled. Rope and pulley on 20 Ft. and larger only. Meets OSHA standards. Type IA extra heavy-duty industrial rating 300 Lb. load capacity.