The D1240-2 Aluminum 40ft 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.