I have a Springer. It ROCKS!!! There is no way I could run several of my dogs without it and keep them safe. They have that husky selective hearing and "come" is not high on their list of "commands I must obey". The Springer saves my shoulders from being dislocated when they try to run on leash. It keeps them safe from traffic, porcupines ect and for my dog aggressive girl, it keeps her out of fights and saves my relationship with my neighbors. They get upset when she beats up their dogs! We both get a good workout. The Springer absorbs almost all of the energy from the dog pulling and stops them from going after wildlife! Kayleigh weighs 100 pounds and is incredibly powerful, but she can not pull the bike over. It's a fabulous device. Best 100 bucks I ever spent!