The PetSafe Rechargeable Bark Control collar uses several features designed to shorten the training phase and promote good behaviour. The bark control collar has a unique sensor that provides the most reliable bark detection available. It also uses temperament learning to decrease and in most cases eliminate nuisance barking.The system has 15 levels of static stimulation. It begins with low-level stimulations. If excessive barking continues the stimulation intensity will increase with each successive bark until the barking stops. Once the dog has learned to reduce the barking, the initial warning stimulations are reduced. As a built-in safety feature, if your dog barks 15 times or more within a 1 minute 20 second period, the Bark Control collar will automatically shut off for 3 minutes.