The D1236-2 Aluminum 36ft Extension Ladder has a duty rating of 225lb and interlocking side rails. The TRACTION-TRED? D rungs are slip resistant and the side rails are interlocking. Heavy duty spring-loaded locks operate smoothly. Durable shoes rest flat or are held in spur position with SHU-LOK? feature. Mar-resistant end caps help protect the surface ladder is leaning against. Exclusive ALFLO? rung joint means TWIST-PROOF? performance every time