Effective pet training requires consistency. The PetSafe bark control collar automatically and consistently corrects excessive barking in dogs. When the vibration of your dog's bark triggers the sensor's probe, a safe but annoying static correction is administered through the contact points. The bark control collar starts with the lowest level of correction and then increases through 6 levels each time your dog barks within 30 seconds. If your dog does not bark again within 30 seconds, the control collar resets itself to the lowest level of correction. Along with each static correction, there will be an audible beep. For safety, the collar shuts off for 3 minutes if your dog barks 15 times or more within 50 seconds. Powered by a 6 V PetSafe RFA-67D-11 battery (included), the collar has a low battery indicator to show you the operating state at any time. This bark control collar is suitable for dogs from 3.6 kg and up.