Petzl Stop Descender DESCEND WITH EASE: Self-braking function allows you to easily stop and hold your position on rope. EASY TO USE: Device can be rapidly installed or removed from the rope without disconnecting it from the harness. LIGHTWEIGHT: Only weighs 326 grams and is compatible for single ropes 9-12 mm in diameter. MULTIFUNCTIONAL: May also be used to ascend short distances with the addition of an ascender and foot loop. DURABLE MATERIAL: The STOP is made out of aluminum bobbins.