The highly advanced Terminator 2 bark control collar will stop your dog from barking faster than any other device made. It uses gradually increasing shock stimulus, plus gradually increasing sound stimulus to quickly teach your dog to stop barking. The Terminator 2 is designed to quickly cure even the most stubborn barker with a minimum of pain. It first applies a tone followed by progressively increasing tone and shock stimulus as your dog's barking persists. If your dog is quiet for 30 seconds or more, the Terminator 2 resets to the mildest correction level. In this way, your pet needs only to experience the higher shock levels a few times before learning that the mild sound and shock stimulus is a warning of stronger corrections to come. Your pet will quickly learn to stay quiet at the mild correction without having to suffer the more intense stimulus. This technique of progressively increasing sound and shock is not only more humane; it is more effective in breaking a nuisance barking habit than conventional shocking bark control collars. The Terminator 2 does not need uncomfortable probes to sense your dog's bark. It uses a built in non-invasive microphone and High Tech Pet's, Sure Sense voice recognition system. The processor monitors the sound wave pattern and, much like your ear, is able to tell the difference between the bark of a dog and stray sounds in the environment. This ensures that only your dog's bark will set off the unit with virtual 100-percent accuracy.