The Ultrasonic Bark Control Collar uses an ultrasonic tone to deter nuisance barking, giving you peace and quiet wherever you and your dog go. Whenever your dog barks, he'll hear a high-pitched sound that's inaudible to most humans. The harmless yet annoying ultrasonic tone stops as soon as he stops barking, which quickly and effectively teaches your dog to stop barking. The collar is lightweight, water-resistant, and comfortable so your dog can wear it at home, the vet, the park, or anywhere he likes to bark. A low battery indicator will let you know when to change the 3-volt lithium batteries.