I have used this on my dog almost every day for a week now and honestly it really corrects his behavior extremely fast. I suggest you start in the lowest levels first, as you don’t need to start high for then to learn. I personally have the beep sound on 2, the vibration on 1 and shock on 1. Which is the lowest setting and literally I only used shock twice since in a week. (Both times I first used beep and gave him the command, second time used vibration and since he continued to not listen then used the shock) he screamed bloody murder which broke my heart no joke. But he did correct his behavior right away. This is in the lowest setting so I don’t see why anyone should go higher unless your dog doesn’t care but be careful it’s pretty sad to see. I love it though cuz my dog used to bark at every other dog, bark at my neighbors from the backyard, pull the leash, basically he was in charge. Now I’m in charge and his a really good boy. I don’t plan on ever using the shock , if possible I been using only the beep and vibration and it has worked perfectly. Suggest a to anyone who wants to correct their dogs behavior. FYI my dog is 1 1/2 years old. So it work no matter the age.