Pull on the lead attached to the control ring, and you have complete control over the dog's head. The theory is that if you control the head, you control the body. The promise system is much more humane than any other training system. It gently guides the dog to follow instructions. There is no choice in the matter for the dog, so the dog obeys.
Reinforcement is positive without yelling, tugging or choking.
One of the benefits of the promise system is that when you make a correction, it is with a very gentle pull on the lead. This pull automatically turns the dog's head toward you, giving you the dog's attention. With many dogs, maintaining attention is one key to maintaining control. The halter also works with the dog's instincts. Dogs tend to pull against pressure.