I initially reviewed this product after a few days use and a marked improvement in my noisy little terriers behavior. After 3 weeks, I am sufficiently impressed to add to my earlier review. It has simply done the job perfectly. My "Rosie" is now perfectly quiet when the door bell rings, does not go berserk when people walk their dogs past the house, and, above all, she is also almost totally quiet when in our car with our labrador, so now we can enjoy walks in the country again. This, the first time for the four years we have had her. For those who are concerned about the "shock" feature, Rosie quickly learned her lesson, and has only activated it twice since we have used it, she always stops after one bark and hears the warning signal. As I said on my earlier review, she loves having it on because she knows she will be rewarded with a biscuit treat when it's put around her neck.