The D4 Work/Rescue Descender features a unique and innovative cam action, which offers precise control at slow or fast speeds. The progressive cam works by way of one cam operating inside another cam. The D4 has a 240kg (500lbs) Working load limit which means it is suitable for two-man rescue, without the need for the creation of extra friction. The handle mechanism is designed to rotate through 360º making its use easier and simpler. The handle itself is made from aluminum rather than plastic and is coated in a specially chosen paint which provides extra grip. Cleverly, the handle rotation is accompanied by audible clicks which help the user identify the correct position of the handle. A great option of chairlift evacuation.