I bought this device and used it as per the instructions. Our 18 month labrador chased after anything and wouldn't respond to "come here". He was manageable around the house but we had no control outdoors.
His behaviour changed after the first "shock" episode. I only used the beep once when he had careered off after flushing up pheasant and not responded to my calls to come. He stopped in his tracks and he returned to me for reassuarnce and a reward for coming back. After a repeat episode on the same walk (when rushing up to a stranger and jumping up) he stuck close to my side off the lead. Unbelievable - we had nearly given up the idea of being able to walk him in a public place and were worried that he would one day caused an incident.
Now, three days later, he is much more responsive to coming when called, keeps closer to me and checks regularly that I'm still there for support. I'm so pleased with this product and even more pleased that it has not been necessary to use the elctric shock. The audible beep was all that our dog needed. A very effective product.