Twist-Proof due to the Alflo rung joints. Slip-resistant Traction-Tred d-rungs. Mar-resistant end caps. Extra heavy duty I-beam rails. Thick guide bracket engages full fly rail. Smooth operating pulley design. Enclosed shape protects pulley. Base and fly separate easily for use as an extension or two single sections. Rubbed spring loaded locks operate smoothly. Guide brackets for durability and smooth operation of fly section. Rugged shoe rests flat or is held in spur position with Shu-Lok feature. Equipped with rope and smooth operating pulley except for No. D1516-2. Dimensions: Rails 3" wide; Flange 1-1/8" wide; Rungs 1-3/4" wide; Base width 18-1/8" outside rails. Length of extension ladders when not extended is half the total length of the sections. Rental.