This collar is the humane and painless way to teach your dog to stop barking with harmless ultrasonic sound. The collar is adjustable- one size fits all sizes and breeds. It comes with two sensitivity settings (high or low) and two volume settings (audible and ultrasonic). It can not be activated by other dogs barking. A LED indicator will light when the unit is activated. The collar is water resistant and includes an On/Off button. Two AG10 button cell batteries are required to operate the unit and are included. The Bark Stop Collar measures two and one half inches x two and five-eight inch x one half inch.