PETZL Simple Descender IT'S THAT SIMPLE: Very easy to use; the rate of descent is controlled by varying the grip on the free end of the rope. FITS YOUR ACTIVITY: Design makes it good for descending tight passages. MULTIFUNCTIONAL: Spring clip allows the rope to be inserted without removing the device from the harness. DURABLE MATERIAL: Made out of aluminum bobbins. LIGHTWEIGHT. The SIMPLE weighs only 240 grams and is compatible for single ropes 9-12 mm diameter.