It works with ropes up to 12mm. Tempered duralumin cheeks and capstans. Stainless steel screws. Spring clip allows the rope to be inserted without removing the device from the harness. The hole In the bottom cheek allows installation of the carabiner directly on the descender with some advantages: 1: in case of heavy loads on the downwards end of the rope the head of the descender cannot accidentally enter into the carabiner 2: the rate of descent is more easily controlled and stop more effective 3: you have just a carabiner instead of two on the harness. Anyway, it is still possible the classical use with the carabiner on the harness. It's possible to change the position of the capstans four times in order to allow a more regular worn out and postpone the replacement. Strength: 22kN (13kN on the bottom attachment point). Weight: 245g. Use: caving. NOT FIT TO PROFESSIONAL USAGE.