PETZL Rack Descender MULTIFUNCTIONAL: The number of bars engaged on the rope may be adjusted at any time to obtain the desired amount of friction. ROPE CARE: Good distribution of friction and heat helps preserve the rope. SAFETY FIRST: The RACK does not twist the rope. COMPACT AND LIGHTWEIGHT: Only weighs 470 grams and is compatible for use on single rope (9-13 mm) or doubled rope (8-11 mm). DURABLE MATERIAL: Made out of stainless steel frame and aluminum bars.