I assume you are talking about Invisible Fence Kitty and we have it and love it. It does flip people out sometime when they see our 100lb dog in the front yard and he will not run into the street after them, funny to watch.
Some dogs can get through it but our original dog a chocolate lab and Bailey who is a cross between a choc. lab and german shorthair pointer never has. The collar the dog wears sounds a tone prior to the wire and never gets close to getting shocked. We highly recommend it, good luck.