The Ultrasonic Bark Control is behaviourally activated and emits an ultrasonic tone when its microphone detects barking. Startled by the tone which is inaudible to most humans, the dog should stop barking. The water resistant collar is suitable for use with dogs over 3.6 kg. This collar is suitable for dogs over 3.6kg and with a neck size of up to 71cm. It is water resistant and has a low battery indicator as well as an on/off switch for longer battery life. Suitable for small, medium and large sized dogs. Manufacturers 3 year guarantee.