Before I review this product, I would like to make a comment on the packaging. It is perhaps the most difficult to open packaging that I've ever encountered, and can actually cause you harm when doing so. Like many products, this one comes encased in a hard plastic shell, the type that requires the use of a very sharp scissors or box cutter to open. The difference between this and the others, is that in addition to the hard plastic, there are 4 areas on the plastic front that are stamped/locked, so that regardless of how you open the package, you'll have the additional chore of trying to rip apart the 4 sealed/locked areas. It's absolutely mind boggling that a company would come up with such a poor design. At first, I tried using a scissors to break through the plastic. When that failed, I brought out a box cutter and cut all the way around the circumference of the transmitter. Once done with this, I struggled so much to rip apart the 4 sealed areas, that I ended up cutting my hands in several locations. I called up the company and told them that their packaging was downright dangerous to open. They explained to me that it's done this way, so that thieves won't be able to open the item and steal it from a store. In this respect, I guess they're correct. If a thief attempted to do so, he/she would become so frustrated that he/she might decide that it's just a lot easier to rob a bank. At any rate, although the packaging is absurd, I'm not deducting any points, as this is a review of the product, not how it's packed. After bandaging up my hands from opening the package, I read the easy to understand instructions for setting up the device. I should note that the reason for my purchase, was that my cat was peeing in our dining room, and I needed to find a way to keep him out of there. The round transmitter requires 3 AA batteries, while the receiver comes with a set of tiny silver ones like you'd find in a watch. The transmitter has the ability to be set for a distance of 2 feet to 12 feet in diameter. It also comes with the ability to set it for additional receivers, should you need to use the device for more than one pet. For this, you'll need to purchase an additional receiver collar. I set the transmitter up for the 12 foot diameter, and used the included tool to test its effectiveness. I found that it did cover an area that was 12 feet wide, but there were some dead spots within this range. Next, I decided to see what the static shock was like before placing the receiver on my cat. To be quite honest, it was slightly painful to me, so I can imagine what it would be like for a small animal. It's not something that I would recommend, unless you're in a situation where it's absolutely necessary to correct problem behavior. I really didn't want to use it on my cat, but I also didn't want him peeing in the dining room. The use of the device won out. My next step was to place the receiver around my cats neck. I did so, than removed it, so that I could adjust it to the proper size. I put it back on, brought him over to the "static" zone and to my surprise, nothing happened at all. I determined that the problem was that the hair around my cats neck was so thick, that the 2 prongs that are supposed to touch the skin, were only touching his hair. I brought out a scissors and tried to trim his hair, but he totally freaked out. Next, I brought out an electric haircut trimmer, and trimmed his hair down to the point where the prongs would be able to touch the skin. Again, this was not an easy task, as my cat freaked out again when he heard the sound of the trimmer. At this point, I was feeling extremely guilty and I really didn't want to use the device, but knew that I had to. I placed the receiver around his neck for the second time, than brought him back to the "static" zone. This time, it worked immediately. As soon as he entered the zone, he switched direction and ran off like a cheetah. I immediately removed the receiver from his neck and let a week go by. He did not return to the dining room, nor did he pee anywhere else in the house. A week later, I placed the receiver on his neck one more time. As a reinforcement, I brought him back to the "static" zone and he immediately ran away. Apparently my problem is solved and unless I encounter any more behavioral problems, I'll never use the product again. The bottom line is that this pet barrier works as advertised, but is not the most humane method of teaching an animal not to enter a certain area. It's listed on Amazon as being a teaching aid for dogs, however when I spoke with a representative from the company, they said it is also designed to be used on cats. My cat weighs 11 pounds, which is well within the acceptable limit for it's use. It can actually be used on pets weighing a lot less, so I can only imagine how painful the static shock would feel to them. Pros: More or less works as advertised. Easy to set up. Easy to use. Quickly teaches your pet not to enter "no pet" zones. Collar is adjustable to any size pet. Transmitter can be set for an area from 2 feet to 12 feet in diameter. Comes with a tester so that you don't accidentally shock yourself. Company representatives are very friendly. Cons: Infuriating packaging I consider shock sufficient enough to be considered inhumane. Receiver collar is uncomfortable, as prongs have to touch pets neck. Pets hair may need to be shaved for prongs to work properly. Would I purchase this again: Yes, but only if every other solution failed to work. Rating: 3.5 stars