I have 7 dogs, Kelpies, Cattle dogs and a Mastiff. I have a BP 504 Barkless Pro for each of my dogs for when we are in town and can not recommend this product highly enough. It is EXTREMELY easy to set up, and EXTREMELY effective. My dogs are used to moving livestock and on our town block get over stimulated and triggered by kids riding their motorbikes backwards and forwards along the front fence line and other "town" distractions. Pre collars it was a nightmare trying to keep them quiet. Post collars is a whole different story. I love the fact that these collars have multiple settings and an automatic function which increases in severity as the barking continues. The belt type collar is excellent as it doesn't become loose during the day as the buckle locks into a hole...I have had terrible trouble in the past with the adjustable collars becoming ineffective because the plastic keeper slips and lengthens the strap as the dogs move around and play meaning that the box is no longer in contact with the dog's skin (and can also flip upside down 🤦‍♀️). I've also had a lot less movement of the collar (box) sideways on the dogs neck than I have had with collars in the past. My dogs learnt within hours not to bark when this collar is on. I have tried a number of barking collars from different suppliers in the past, all of which have been a dismal failure. I will only use this one from The Dog Line in the future. Customer Service from Colin, Carmen and Penny is exceptional...they go above and beyond, are courteous, polite and friendly and extremely knowledgeable about their products. After watching my experience, my boss bought 2 of these collars and has had similar success and another friend has also just bought one. I have other friends who will be purchasing them in the future. These are well worth the investment if you have a dog that barks.