We have this dog, a 2 year old boxer. She is very high energy and we can't keep her in the yard. As soon as that door opens she bolts for it and is gone. She doesn't even come home at night. Anyway we finally decided to buy an invisible fence. I flagged the yard today, and took her with me on a leash to show her what I was doing, then turned it all on and put the collar on her. Walked her back out on the leash, and she got zapped twice. Now she has a huge fear of little white flags and won't even walk around the yard! I do have to say though that this is the first day ever that I can get out the door without her running for it, she is hiding behind it....Ahhhhhh dogs!