The D1516-2 aluminum extension ladders have a duty rating of 300 lb and have extra heavy-duty I-beam side rails. The base and fly sections separate easily and can be used separately. Guide brackets help to ease operation when raising and lowering the fly section. The exclusive ALFLO(R) rung joint means TWIST-PROOF(R) performance every time. The side rails are extra heavy-duty I-beam rails and the aluminum TRACTION-TRED(R) D-rungs are slip resistant. Rugged, spring-loaded locks operate smoothly. Mar-resistant end caps protect the surface ladder is resting against.