Max broke for the door everytime it opened. We have neighbors who walk their dogs and if Max was out he was as good as gone. We constantly took him out to potty on a leash and poor guy really couldn't be trusted to run and play even. He would wonder off if he saw, a person, bird, bunny anything. He wasn't trying to run away but curiosity always prevailed! We didn't want to fence our front yard and the fence in our back yard was more like a 4 rail fence that wouldn't contain him. So....we installed an underground invisible fence AND IT IS WONDERFUL!!!! Now when my kids leave the front door open or when a visitor arrives Max can run out to greet them and we don't worry. He play all over the yard, he goes potty without being on a leash and he gets so much more exercise. He seemed to learn the boundary for the fence within a couple of days and has only tested it once after training. My neighbor and her dog walked by and off he went. He got stung and did an about face, ran to porch and sat down. Now he doesn't even attempt to venture beyond where he hears the warning tone. We diligently watch him becuase I don't believe anything is full proof but we live on a relatively quiet street. Life is good!