Triggered by the vibration of your dogs vocal cords, the collar will first give the dog a warning beep and then progressive static corrections. If your dog continues to bark, the static correction automatically increases to the next level. Since this collar senses your dogs throat vibration rater than the actual noise of the bark you can rest assured foreign noises or other dogs barks will not set off this collar. The Nylon collar of the NoBark Static will adjust from 6-22 inches which will fit most breeds of dogs. The NoBark Static is a very compact and lightweight collar (2oz) and is recommend for dogs 8lbs or larger.