Vastar No Bark Dog Collar Electric Training Anti Bark Shock Control with 7 Levels Button Adjustable Sensitivity Control, Stimulation of No Harm Warning Beep and Vibration for 15 to 120 Pounds Dogs Vastar No Bark Dog Collar Electric Anti Bark Shock Control with 7 Levels Button Adjustable Sensitivity Control, Stimulation of No Harm Warning Beep and Vibration for 15 to 120 Pounds Dogs High-quality Electronic Anti-Bark Dog Collar and Sends harmless warning sound and shock to the dog whenever it barks Protect the dog Lightweight receiver, Unique bark terminator, Replaceable 6-volt Battery and Low battery consumption, Effective on a 15-120pounds dog The stimulations repeat through 7 correction levels, the intensity gradually increases until the dog stops for thirty seconds. If the continuous stimulus reaches the 7 levels, then the Collar will stop working for 1 minutes to protect the dog It's not suggested to use it for puppy, especially below 8 lbs, but you maybe can have a try carefully. If the dog is too small, you must use it under the guidance of the master to avoid unnecessary harm to your dog, because the stimulation for the puppy will be a little strong