The CLIX No-Bark collar has a microphone which detects barking and automatically emits either a sound or a vibration to interrupt the dog's barking. How Do You Adjust It? 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 - and the large No-Bark collar has 3 levels - low, medium and high. CLIX No-Bark Collars are a low cost solution, cheaper than the alternative spray training collars. The collar straps on the units are adjustable over a wide range to ensure correct fit.INCLUDES BATTERIES, these are low cost and easy to replace. The CLIX No-Bark Collars are NOT waterproof. Will not deter a dog from responding to home threats or from acting in territorial defence The CLIX No-Bark Collar comes in two sizes - small dogs 6- 22 pounds and large for dogs over 22 pounds. Affordable Lightweight Simple and easy to fit On/off switch 2 settings: vibrate & sound NO ELECTRIC SHOCKS!