Trouble with shock collars is you have to BE there to shock the dog. The dog soon figures out whether you are there and whether the collar has the battries in. I can't say it long or loud enough..........FENCE!! or outside dog run. If it's not cars, it'll be something else........poison, antifreeze in the neighbors drive, neighbors with a grudge against dog shit in their yard.....if you love your dog, either fence your yard or buy a chain link run!!!!