We put in a black aluminum fence with a 4" gap between rails which we thought would keep our new Parson Russell Terrier contained. We discovered otherwise when she jumped through to chase a squirrel. After two escapes we started to search for a solution and found Dog Proofer. My husband thought it would ruin the look of the fence but even he was pleased after we installed it. You can barely see it and we finally feel that we can let her out without having to monitor her every move. It was pretty easy to install, even on the gates. Definitely recommend this for a dog that can squeeze through your existing fence.