I got these for my dad's 3 chihuahua's. At first, the beep and vibrate worked and they would quiet. Now they have figured out that it just beeps and vibrates when they bark so it isn't effective. I realize it has a shock option but my dad is 100% against using the shock on them. I gave 3 stars because it was effective at first but they grew accustomed to them and no longer react to the collars. I am not knocking off stars for the shock since it isn't being used. I bought these with the impression that the beep and vibrate would work without needing to resort to shock. If I can convince him to try the shock, I will update my review appropriately. Assuming it is effective anyways. They seem quite determined to bark anyways.