This device was my last resort. I'm so glad I stumbled upon it. I have tried for years to get my dogs to stop barking under certain circumstances. Dog whistle, yelling, spraying with water, closing the curtains, you name it. I've tried it. I have three dogs, an Irish Setter, a Bichon Frise and a Maltese cross. There are some situations where I have not been able to quiet them, for several years. Here are the worst.The dogs can smell/hear the mail carrier across the street, even before he/she comes into sight. That's about four houses down. They bark uncontrollably until the carrier has passed and is out of sight. We're talking about 4 minutes of very loud incessant barking six days a week. I've tried everything and given up. My Bichon has a bark that goes right through your body. He's a true Yapper. He drives me crazy! I received this device before the daily bark-fest and hung it up by the window where they love to bark. When the carrier reached his/her designated spot, the dogs went off as usual. I corrected , "Hush", and praised them when they stopped barking. I remained with them correcting and praising as needed, until the carrier left their bark-zone. The Setter and Maltese figured it out really quickly. The Yapper was quieter, but did not stop completely. On day two, the Setter and Maltese let out a couple of barks and then stopped without a correction. I praised them profusely. Mr Yapper needed some reminding, but he stopped when I corrected him. He was praised profusely. Day three came and went. I had to check for the mail that day. This cant be happening! Just a fluke. One week has passed and I haven't heard a whimper of a carrier alert. OK. I believe it works now.The second most obnoxious time is when the doorbell rings or someone approaches the door. I get a lot of deliveries and of course they ring the bell. Crazy dogs again. I don't get deliveries every day so I'm still working on this one, but there has been an appreciable cut down in the barking. I'm sure that "this, too, will pass" after some more reinforcement.There are other situations that didn't need any correction from me. No more alerting when somebody walks by, with or with a dog. I praised them profusely for not barking. I've had a week of peace and quiet! Finally, a last resort that is truly the last! If you have had years, or less, of trying everything else to quiet your dogs like I have, give this a try. I was sure I was wasting my money again, but that was not the case.Love it!Try it!