The Clix No-Bark Collar helps you stop your dog's excessive barking effectively without hurting him with a shock collar. It has a microphone which detects barking and automatically emits either a sound or a vibration to interrupt the dog's barking. The collar has two deterrent settings-either to vibrate or to emit a high pitched sound. Choose the one that the dog responds to best. CLIX No-Bark collars also feature different levels of sensitivity, so you can adjust the noise threshold. The small No-Bark collar has 2 levels of sensitivity - low and high. Small size for dogs between 6 and 22 pounds.