Oternal Electronic No Bark Dog Training Collar with no Harm Warning Beep and Shock for the 15-100 Pounds Dog (Gray) High-quality Electronic Anti-Bark Dog Collar and Sends harmless warning beep and shock to the dog whenever it barks 7 sensitivity levels (1-7) adjustable for the different size of dogs barking through the Lightweight receiver, replaceable 6-volt Battery Effective on a 8-120pounds dog Note: Don't encourage you 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