It works, when you figure it out. The instructions, such as they are, are on a one-sided sheet of xeroxed letter sized paper. The only illustration was a photo of a part of the remote control. Many other items were in the package and I would have appreciated a sheet of paper labeling each one and certainly better instructions. Okay, all that leaves something to be desired, but the thing does work. I had a hard time making the collars small enough to work on my two 12 pound dogs. And, although I have used them for only a week, one of the screws on one of the receivers managed to unscrew itself and fall off. I cannot figure out how that could have happened! And, sometimes one of the buttons (they recede below the surface when depressed) gets stuck! The first time it happened I didn't even notice for a bit--my poor dog. Luckily, that time I was only using the vibration function. Vibration is enough for my dogs. It doesn't hurt them at all, but startles them just enough to be effective when they start barking like little nutty doggies when other dogs are being walked past the house. I have tested the first shock on myself and have only used it a couple times with the dogs. I don't think it would hurt them, but I also think for my little ones I don't need to go that far. I am glad I bought this, especially because I control when it is used instead of it automatically going off when they bark, and because it controls two dogs rather than one. However, if I don't find the missing screw and its rubber cover, I may only be able to use it on one dog at a time.