My wife an I were convinced to purchase the wireless containment system (we call it the 'zapper') by our neighbor. She has a very active golden retriever named Cindy who was always running out of their yard. That is, until they bought one of these. After about a week of having a 'zapper' Cindy was behaving wonderfully. She would go right to the edge of her yard and stare longingly at my kids playing ball 10ft away from her, but she would not cross over into our yard. Amazing!
We also have a dog who is a 'runner'. If our dog, Fenway, ever got out the door without a leash on he was off to the races. After seeing how effective the 'zapper' was with Cindy we decided to get one for Fenway. The first couple of days we were starting to regret our decision a bit because Fenway was NOT happy about the mysterious zaps he was getting. He got so freaked out about it that we literally had to drag him off the back porch because he was terrified of getting zapped in the yard.
However, we have now had the zapper for almost a month and we couldn't be happier with it. We spent the first week training Fenway and showing him around his new boundaries. He is now loving his new found freedom! He no longer is bound by a leash or a run in the back yard. He is free to run and frolic anywhere within his boundaries. We have looked at each other a few times and asked why we didn't get one of these earlier. It is making our lives and Fenway's life much happier.
We also looked at the invisible fence products, but we felt that this one was a better idea. The major problem we were concerned about with the invisible fence is that once your dog has broken through the 'zap zone' he is home free. With this product, the dog keeps getting zapped until he comes back into the safe zone. The only drawback to this product is that the 'safe zone' is circular only. This wasn't a problem for us because have a large back yard and could comfortably use the full 90ft radius. However, if you have an oddly shaped or long, thin yard you won't get the maximum benefit of this system.
In short, I LOVE this product and highly recommend it!