Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Not for small dogs

The amount of vibration needed to cause the collar to "correct" your dog is set too high. The instruction manual tells you to rub it along carpet to see if it's working properly. In order to get it to work I had to do this excessively. I couldn't see how that much friction to get it to go off would be anything close to a dogs bark. Good idea in theory to rely on vibration rather than sound, but without a way to change the sensitivity this would probably only work for large dogs. Long story short, 90% of the time it never worked. BIG waste of money.