Zacro DC395 Dog No Bark Collar for Bark Control with 7 Levels Adjustable Sensitivity Control, Electric Anti-Bark Shock Collar for Dogs, 15-120 lb, Fits for Large and Medium Dogs Zacro New Model Bark Collar was updated with improved anti-bark chips which will be more Humane, effective and easy to use. Stops unwanted barking with progressively increasing warning sounds and harmless static stimulus. 7 sensitivity levels (1-7) adjustable for the different size of dogs barking and specific environments through the "+"/"-" button The stimulations repeat through 7 correction levels, the intensity gradually increases until the dog stops for thirty seconds Lightweight receiver, unique bark terminator, effective on a 15-120 pounds dog Adjustable nylon collar senses vibration in dog's throat during barking