Suddenly the dog sees something and instinct makes it start running. This develops enormous forces that can hurt both dog and owner. That's why Curli has developed a rope leash that significantly reduces the jerk when a dog is restrained. The rope's core and sheath adapt to the tension applied to them. This is more comfortable for everyone and ensures safe transmission of commands. Facts about Curli Stretch Comfort Leash: For dogs up to 25 or 40 kg (8/10 mm). Shock absorbing rope for stress-free communication. Ultra-soft nylon rope for the best possible grip, control and safety. Dispenser for dog bait bags. Snap-in safety hook.