Tension: A force of 35KN (about 3500 kg) for the eight-character ring. Material: 7075 aviation aluminum solid material with high strength, light weight, easy to carry and so on. Dimension: 8-shaped ring thickness 12.8 mm Principle: The eight-ring principle is the friction between the benefit rope and the descender to slow down the descent speed or to brake. It is a common descender. Directions for use 1. Fold the rope. 2. The rope passes through the ring. 3. Circumvent the rings 4. Link up the seat belt and hold the rope with both hands when descending.